The smell of freshly baked bread awakened in mr. hutz vivid memories of his early childhood. the aroma apparently acted as a powerful:
a) echoic memory.
b) retrieval cue.
c) implicit memory.
d) spacing effect.
e) mnemonic

B) retrieval cue.    

Explanation:

Retrieval cue: In psychology, the term retrieval cur is defined as a prompt that is being used by a person to trigger for the retrieval of the long-term memory. The information related to memory retrieval can be accessed without being cued. The retrieval cue helps a person to remember memory related to his or her life. If a person makes a new memory, then the person must include information related to the situation as well that will act as a trigger while accessing the memory.

In the question above, the given statement refers to a retrieval cue.

sadly i believe the answer is d