Answer: The correct answer for the blank is -
A. memory consolidation
Explanation:
Memory consolidation can be described as a process of stabilization of a short memory into a long term memory after it is acquired. According to this process, dreams (which are the mental processes during sleep time) can be useful in the formation and the rehearsal of memory so that trace memory can be converted to stabilized long term memory.
Thus, option A) is the right answer.