A Picture Fell Off the Wall Startling James Quite a Bit

A picture fell off the wall startling James quite a bit, making him jump. His roommate comes home a couple minutes later and his shutting the door makes James jump again though it doesn't typically. The reason he jumps the second time is that the falling picture
________ to loud noises.

A) made him vulnerable
B) habituated him
C) made him more aware
D) sensitized him