Final answer:
Memory T lymphocytes can survive for a long time, even for a person's lifetime. The lifespan of B lymphocytes, or memory B cells, can vary depending on the individual and the specific pathogen they have encountered.
Step-by-step explanation:
Memory cells are a type of lymphocyte that can survive for several months or years. In the case of T lymphocytes, they can survive for a long time, even for a person's lifetime. On the other hand, the average lifespan of B lymphocytes, also known as memory B cells, can vary depending on the individual and the specific pathogen or disease they have encountered. Some memory B cells can survive for a few years or even several decades, while others may gradually die off if the pathogen they were specific to is not encountered again.