Part A:
The correct inference about Daniel's "midlife crisis" noted "affectionately" by his friends is:
C. Daniel is reflecting on the artistic goals and achievements of his youth and wants to feel that happiness again.
Part B:
The sentence from the text that best supports the answer in Part A is:
C. Looking back at his teenage years when he'd spent so much of his time and energy creating works of art, he realized that he had been like a butterfly then, free and light and perfectly content.
This sentence indicates that Daniel is reminiscing about his past artistic pursuits and the happiness they brought him, contributing to the inference about his midlife crisis.