It is ___ to call than to write.

Correct Answer: C. Quicker

The correct answer is C. Quicker.
The sentence should read:
“It is quicker to call than to write.”
Explanation:
Quicker is the comparative form of “quick,” which is used when comparing two things (in this case, calling and writing).
The structure of the sentence is making a comparison between calling and writing, so we use the comparative form “quicker” without the need for “than” after “quicker.”