<span>Cytotoxic T cells recognize specfic antigens on the MHC sites to respond to an infection whereas NK cells are innate response and don't rely on antigen.</span>
<span>An example of concentric contraction is doing a biceps curl. The curl exercise is targeting the biceps muscles on the front of the upper arm and only several muscles assist during the movement. Moreover, concentric muscle contraction is a type of muscle activation that increases the tension on a muscle as it shortens and this activation begins the process of muscle strengthening and hypertrophy. </span>
Answer:
Because they don't like the noises
