C. After his master said that “learning would spoil” him, Douglass continued his education on his own.
Explanation:
This seems like the correct answer because the answer choice says Douglass continued to learn on his own. Answer Choice D just says that he got interested in the American Revolution, not that he began to grow an interest in education. Answer Choice A has nothing to do with learning, only recording information. And Answer Choice B just says that Douglass's mistress read to him for a little bit until her husband told her to stop, which has nothing to do about education.
