Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large scale destruction caused by violent winds, very heavy rainfall and storm surges.
Tropical cyclones originate and intensify over warm tropical oceans.
The conditions favourable for the formation and intensification of tropical storms are :
1. Presence of Coriolis Force ( that's why the winds in northern hemisphere takes right & winds in southern hemisphere takes left turn)
2. Pre existing low pressure Area ( As it is tropical region there exist low pressure)
3. Small variations in the vertical wind speed (even though it is a tropical region the solar insolation absorbed by water is not uniform everywhere so it causes pressure difference which in turn leads to wind directions and speed)

In addition to above mentioned,
4. Large sea surface with temperature higher than 27 degrees
5. Upper divergence above the sea level system
are also reasons for the formation and intensification of tropical storms.
So, the answer is D.

Conditions Favorable for the Formation and Intensification of Tropical Storms

The formation and intensification of tropical storms, such as hurricanes, cyclones, and typhoons, are influenced by several factors. Among the given options, all three conditions are favorable for the development and strengthening of tropical storms.

1. Presence of Coriolis Force
The Coriolis force is an apparent force that is caused by the rotation of the Earth. It deflects moving objects, including air masses, to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The presence of the Coriolis force is crucial for the formation of tropical storms, as it helps in establishing the cyclonic circulation required for their development. Without the Coriolis force, the air would simply move in a straight line, and the rotation necessary for the formation of cyclones would not occur. Therefore, the presence of the Coriolis force is a necessary condition for the formation and intensification of tropical storms.

2. A Pre-existing Weak Low-pressure Area
Tropical storms typically form and intensify in regions where there is a pre-existing weak low-pressure area. Low-pressure areas allow warm, moist air to rise and condense, leading to the formation of clouds and precipitation. As the air rises, it creates an area of low pressure at the surface. This low-pressure area acts as a fueling mechanism for the storm, drawing in more warm and moist air from the surrounding environment. The convergence of air towards the low-pressure center strengthens the cyclonic circulation and contributes to the intensification of the tropical storm. Therefore, the presence of a pre-existing weak low-pressure area is a favorable condition for the formation and intensification of tropical storms.

3. Small Variations in the Vertical Wind Speed
Small variations in the vertical wind speed are also conducive to the formation and intensification of tropical storms. Vertical wind shear refers to the change in wind speed and direction with height. Strong vertical wind shear can disrupt the organization and development of tropical storms by tilting or shearing the storm structure. However, when there are small variations in the vertical wind speed, it allows for the vertical stacking of warm, moist air, which is necessary for the storm to strengthen. This allows the storm to maintain a well-defined circulation and consolidate its energy. Therefore, small variations in the vertical wind speed promote the formation and intensification of tropical storms.

In conclusion, all three conditions mentioned in the options are favorable for the formation and intensification of tropical storms. The presence of the Coriolis force, a pre-existing weak low-pressure area, and small variations in the vertical wind speed play crucial roles in creating and sustaining the cyclonic circulation necessary for tropical storm development.