Respuesta :
The answer is D. The lock-and-key mechanism is instrument proposed in 1890 by Emil Fischer (1852–1919) to clarify authoritative between the dynamic site of a compound and a substrate atom. The dynamic site was thought to have a settled structure (the bolt), which precisely coordinated the structure of a particular substrate (the key).
The correct answer is A. Lock and key mechanism is used by an enzyme and its substrate. This is basically used in case of a single ezymes and its substrate. This mechansim was hypothesized by Emil Fischer. The lock is the enzyme and the key is its substrate, which possess a structure similar to that of the key hole of the lock.