Common cold spreads through:
The common cold is a viral infection that primarily affects the nose and throat. It is caused by different types of viruses, most commonly rhinoviruses. The common cold can spread from person to person through various means. Let's discuss them in detail:

Direct Contact:
One of the most common ways the common cold spreads is through direct contact with an infected person. This can occur when an infected person sneezes or coughs, releasing tiny droplets containing the virus into the air. These droplets can then be inhaled by another person, leading to infection. Direct contact can also occur by touching surfaces or objects contaminated with the virus, such as doorknobs or utensils, and then touching the nose, eyes, or mouth.

Foul Air:
The common cold can also spread through foul air. When an infected person sneezes or coughs, the virus can become airborne and travel through the air. This can happen in close proximity to the infected person or in enclosed spaces with poor ventilation. Breathing in these viral particles can lead to infection.

Houseflies:
While houseflies are known to spread some diseases, they are not a common mode of transmission for the common cold. The primary mode of transmission is through direct contact or foul air, as mentioned above. Houseflies may come into contact with the virus if they land on contaminated surfaces or objects, but the likelihood of them spreading the virus to humans is minimal.

Dog-bite:
Dog-bites are not a mode of transmission for the common cold. The common cold is primarily a human-to-human transmission. It is not known to be transmitted through animals or their bites.

In conclusion, the common cold primarily spreads through direct contact with an infected person or through foul air. It is important to practice good hygiene, such as washing hands regularly and covering the mouth and nose when sneezing or coughing, to prevent the spread of the virus.