Final answer:
Natural killer cells differ from T cells in that they can non-specifically attack several types of intruders, like virus-infected cells and cancer cells, without the need for prior exposure to the pathogen, while T cells are highly specific and involve in the adaptive immune response. The correct answer is option b.
Step-by-step explanation:
One of the main differences between natural killer cells and T cells is that natural killer cells are not specific in their targets while T cells are highly specific. Natural killer cells (NK cells) are part of the body's innate immune system and can attack several kinds of intruders, such as virus-infected cells and cancerous cells, without the need for prior exposure or recognition. This is because they recognize cells based on the absence of 'self' proteins (such as MHC Class I molecules) due to infection or transformation. On the other hand, T cells are critical components of the adaptive immune system and target pathogens with high specificity through antigen recognition.
T cells directly attack other cells through a process called cellular immunity and are involved in adaptive immunity, which means that they require a prior activation by the specific antigen presented to them. Natural killer cells, however, do not need specific activation and can identify and destroy infected cells by the altered expression of MHC I molecules on their surface. Thus, the correct option for the question is (b) attack several kinds of intruders.