What is the purpose of the radio public service announcement on make a difference day

Which excerpt best represents the central conflict of “ everyday use”

Then she heard his step on the stair away down on the first flight, and she turned white for just a moment. the phrase "she turned white for just a moment" is mainly used to show that della has very fair skin. is afraid of jim's reaction. is beginning to get an illness. had become extremely angry.

What point is the author trying to make by comparing the travel times of the first transcontinental railroad and the first transcontinental flight?