单选题
Pottery enabled primitive people to boil and steam food, which in turn allowed them to gain ______ from new and more varied sources.
【正确答案】
A
【答案解析】[解析] 句意：陶器使原始人类能够蒸煮食物，反过来这也使他们能够从各种新来源中获得食物。sustenance食物；生计；支持。subsidiary子公司；附属公司。substance物质，物品；实质，主旨。supplement增补(物)，补充(物)；添加物。