Which of the following options best completes the sentence below? The responsibilities of a class president are extensive; __________________, she should not become so involved that she neglects her studies.
A. Therefore
B. Indeed
C. However
D. Especially
Choice C: "However"
The sentence suggests a contrast or contradiction between the extensive responsibilities of a class president and the need not to neglect her studies. "However" is a transitional word that effectively introduces this contrast or counterpoint, making it the most suitable choice to complete the sentence.
Therefore, the Correct Answer is C.