Questions: is an enzyme that destroys bacteria by digesting their cell walls.

The answer is the first one (a): Lysozyme.

Explanation for each option:

a. Lysozyme: This is the correct answer. Lysozyme is an enzyme that breaks down the cell walls of bacteria, specifically by cleaving the bonds in the peptidoglycan layer, which is a crucial component of bacterial cell walls. This action helps to destroy bacteria.

b. Amylase: This enzyme is incorrect in this context. Amylase is responsible for breaking down starches into sugars and is not involved in destroying bacterial cell walls.

c. Trypsin: This is also incorrect. Trypsin is a protease enzyme that breaks down proteins in the digestive system, not bacterial cell walls.

d. Cytokine: This is incorrect as well. Cytokines are signaling proteins that mediate and regulate immunity, inflammation, and hematopoiesis, but they do not directly destroy bacteria by digesting their cell walls.

In summary, lysozyme is the enzyme that destroys bacteria by digesting their cell walls.