The action from a force can cause an object to move or speed up (accelerate), to slow down (decelerate), to stop, or to change direction. Since any change in velocity is considered acceleration, it can be said that a force on an object results in the acceleration of an object.

The correct answer is option 'D' - Speed.

Explanation:

When a force is applied to an object, it can cause a change in its speed. This is because force is directly related to acceleration, and acceleration is the rate at which an object's speed changes over time.

**Force and Acceleration:**
- According to Newton's second law of motion, the force acting on an object is equal to the mass of the object multiplied by its acceleration. This can be expressed as F = ma, where F is the force, m is the mass, and a is the acceleration.
- If a force is applied to an object, it can cause the object to accelerate, either by increasing its speed, decreasing its speed, or changing its direction of motion.

**Change in Speed:**
- When a force is applied to an object, it can increase or decrease the object's speed depending on the direction of the force and the initial speed of the object.
- If the force is applied in the same direction as the object's motion, it will increase the object's speed. This is because the force adds to the object's existing speed, resulting in a greater overall speed.
- On the other hand, if the force is applied in the opposite direction to the object's motion, it will decrease the object's speed. This is because the force opposes the object's motion, resulting in a decrease in speed.

**Other Options:**
- Option 'A' - Colour: The force applied on an object does not have any direct effect on its color. The color of an object is determined by the way it absorbs and reflects light.
- Option 'B' - Mass: The force applied on an object does not change its mass. Mass is an intrinsic property of an object and remains constant regardless of the external forces acting on it.
- Option 'C' - Weight: The force applied on an object does not change its weight. Weight is the force exerted on an object due to gravity and is determined by the object's mass and the acceleration due to gravity. The force applied on an object may affect its weight momentarily if it is lifted or pushed against gravity, but in the absence of any external force, the weight remains constant.

Therefore, the correct answer is option 'D' - Speed, as the force applied on an object can cause a change in its speed by either increasing or decreasing it.