单选题 Catherine doesn't plan her meals very carefully. She just cooks whatever she happens to have ______.
A. on hand B. on her hand
C. under her hand D. at hand

【正确答案】 A
【答案解析】on hand“现有，在手头”；on one's hand“由……照管”；under one's hand“经……亲笔签名”；at hand“在附近；即将到来”。