Which two substances bind using a lock-and-key mechanism

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.

Iam not sure but to me it with be a or dsorry if i was late! hope this ! : )if you really want me to find out the answer that is correct tell me and i will do more research but the a or d makes sense to me.

Ithink you should go back and learn in school rather then here asking questions