Final answer:
The statement that NK cells are said to have memory is False. NK cells are traditionally not considered to have memory, a feature of adaptive immunity; this is associated with B cells and T cells. However, emerging research suggests NK cells may have 'memory-like' functions. Natural killer cells assist cytotoxic T cells in targeting virally infected cells through direct killing and cytokine secretion.
Step-by-step explanation:
Historically, memory in the immune system has been associated with adaptive immunity, specifically with B cells and T cells that can remember past infections and respond more vigorously upon re-infection. However, more recent research has begun to suggest that NK cells might also have a form of 'memory' or 'memory-like' function after activation, although this concept is still being explored and not widely recognized as classical memory.
Regarding the immune response working in concert with cytotoxic T cells against virally infected cells, natural killer cells (Option a) are indeed part of the innate immune response that works alongside cytotoxic T cells. They can directly kill virally infected cells and also secrete cytokines, such as interferons, which can enhance the activity of other immune cells including B cells.