The correct answer is: A. A change in a cell's genetic material.
Mutations occur in DNA as a result of mistakes during the DNA replication (when repair mechanisms don’t fix it) or as the result of environmental factors (e.g. UV light). Mutations can have positive impact, by increasing the genetic variation or can have negative effect, causing the diseases or cancer.
The availability of glucose energy necessary for memory consolidation is most likely to be enhanced by stress hormones.
These hormones, as well as growth hormones, sex hormones, and glucagon, have such an influence on liver that glucose gets secreted into the bloodstream. Glucose is important for many things in our body, and memory consolidation is one of them.