The Timber rattlesnake is now on the endangered species list, and is extinct in two eastern states in which it once______.

【正确答案】 A

【答案解析】thrive表示“兴旺；茁壮成长”。swell表示“膨胀，肿胀”；prosper表示“发达”；D项flourish表示“茂盛；盛行”。