Reduced levels of ______ cytotoxicity have been found in people who are highly stressed:

Natural Killer Cell

The correct answer is Option (3) → Natural Killer Cell

Stress can affect natural killer cell cytotoxicity, which is of major importance in the defence against various infections and cancer. Reduced levels of natural killer cell cytotoxicity have been found in people who are highly stressed, including students facing important examinations, bereaved persons, and those who are severely depressed.