The previous question asks how Katz's attitude toward "today's digital technologies" can best be characterized. The answer, that he is uncertain about their possible effects, is supported in the final sentence of the sixth paragraph:
"If technology disrupts enough, who knows what will happen?"
Choices A, B, and C are incorrect because the lines cited do not support the answer to the previous question Katz's attitude toward "today's digital technologies"; instead, they describe some of his earlier research (choice A) and provide insight only into his initial thoughts but not his final conclusion on the matter (choices B and C).