Final answer:
The recency effect is due to information held in short-term memory.
Step-by-step explanation:
The best explanation of the relationship between Short-term Memory (STM) and the recency effect is that the recency effect is due to information held in short-term memory. The recency effect refers to the phenomenon where items presented most recently are better remembered than those presented earlier. This effect occurs because items in the short-term memory are still easily accessible and have not been overwritten by newer information.