the action or process of classifying something according to shared qualities or characteristics
Answer: natural killer cell
Explanation:
Natural killer cells are referred to as the granular lymphocytes which play vital roles in the immunity against viruses. It doesn't need antigenic activation in order to detect and kill pathogens.
When an enemy cell is present, a natural killer cell secretes perforins, which bore a hole in the enemy cell membrane.
During Transcription Some Letters Are Switched Out.
