While mountain climbing and stamp collecting both require patience, _________ is certainly more physically demanding.

4
writing

The underlined pronoun makes the sentence ambiguous. Replace it with the choice that best reduces that ambiguity.

A

it

B

the sport

C

that one

D

climbing

Correct Answer: B

Choice B is the best answer. "The sport" clearly distinguishes mountain climbing from stamp collecting.

Choice A is incorrect because "it" is ambiguous and could refer to either activity. Choice C is incorrect because "that one" is vague. Choice D is incorrect because "climbing" is repetitive.