Your book explains that brief episodes of retrograde amnesia (e. g., the traumatic disruption of newly formed memories when a football player takes a hit to the head and can't recall the last play before the hit) reflect:.
a. korsakoff's syndrome
b. a failure of memory consolidation
c. temporary post-traumatic stress disorder
d. neurofibrillary plaques

A failure of memory consolidation

Explanation:

Consolidation is a process of stabilizing the memory after the traces. This is perhaps the part of memory encoding or storage, memory. It is also called a memory process. This procedure has been divided into two concepts

Consolidation process initializing the process of long term potentiate.  

Thus in the above context, the brief episode of the retrograde amnesia interrupt newly formed memories. When a football player hits his head and not recall the previous play before hitting reflects the failure of memory consolidation.