Answer:
B. According to Dr. Clemons, “Keats demonstrated a keen sense of delivery.”
Step-by-step explanation:
The difference between options A and B is the position of the final point (.). Option B shows the correct way to position the period in a sentence that contains quotation marks ("). This is because in the US, grammar establishes that the period must end sentences, however, if the sentence to which the period belongs it is enclosed in two quotation marks, the end point must be positioned before the last quotation mark.
However, in England, the letter A would be the correct option, since the grammar of England states that the period must be at the end of the sentence, regardless of the presence of quotation marks.