What's the other term for: explosive or changing very quickly

Which sentence from the text best develops the theme about the importance of compassion for other people? "besides, he was the only person in the whole place with skin nearly as dark as hers." "at first she wanted to intern at her dad's gas station, but her teacher told her she needed to branch out and signed michelle up at the oakcourt nursing home, only 15 minutes away from her house." "still, michelle had been curious, and she felt sorry that erkan had a bad reputation among the staff." "she too had felt like everyone mistrusted her--especially at the nursing home where she was so much younger than the rest of the staff--so she understood how he must feel."