I believe it is C because she struggled in the beginning and she said it in the most simplest way possible that she even she does not understand how she is able to do it.
Answer: In my opinion, it’s measurement is a fundamental aid in the engineering world. You may need to measure things. Say a NASA engineer wants to build a new engine for a spaceship model. They will need to measure many things to get the engine to fit the ship, and to fit all the bits inside. Measure also helps the efficiency, and the quality. You wouldn’t want a MacBook that’s 5 yards long!
The third sentence down is the right answer. It doesn't use slang.
