Question

multiple choice 10 points athletes who want to improve their skills should exercise harder ______ they are comfortable with. without than and because

Explanation:

The sentence implies a comparison. Athletes are being told to exercise harder than the level they are comfortable with. "Than" is used for comparisons. "Without" doesn't fit the context of comparison. "And" is for addition and "because" is for giving reasons, neither of which are appropriate here.

Answer:

B. than