Final answer:
The adaptive immune system is responsible for overcoming a specific virus that causes the common cold through B cells and T cells. Although immunity to that specific virus is achieved, the presence of many distinct cold viruses means a person is not immune to all possible cold-causing viruses.
Step-by-step explanation:
When a person recovers from a common cold caused by a virus, it indicates that the body's immune system successfully eliminated the virus. The line of defense responsible for this is part of the adaptive immune system, which includes lymphocytes such as B cells and T cells. The B cells produce antibodies that specifically target the virus that caused the cold, and the T cells help to kill the infected cells and support the B cells.
Once the body has developed immunity to a specific virus, it can recognize and fight off that virus more effectively in the future. However, due to the large number of cold-causing viruses, such as rhinoviruses, coronaviruses, and adenoviruses, humans can get colds from different viruses to which they have no immunity. Therefore, while a person might become immune to one type of cold virus, they are not immune to all, resulting in the frequent occurrence of colds.