The correct answer is A. People often resist change.
With these words, he is telling Ralph that he and Mahailey will always be old-fashioned. Even more than that, he's saying that he wants it that way -- "you'd better let us be." He's telling Ralph not to bother trying to change their minds.
These words have nothing to do with hard work or technology, so answers B. and D. are wrong. Finally, answer C. is wrong because he is telling Ralph NOT to be persistent. He's saying that Ralph will never persuade them. Therefore, the best answer is A -- they are resisting change.