检索题。scifinder主题检索中输入：preparation of biodegradable polyester for drug delivery，进行检索后结果有：

A、系统分别检出"preparation", "biodegradable polyester"和 "drug delivery"三个组词各自的文献结果数;
B、系统给出"biodegradable polyester" and "drug delivery"组合的文献结果数;
C、系统给出"preparation" and "biodegradable polyester" 组合的文献结果数;
D、系统检出了"preparation" and "biodegradable polyester"and "drug delivery"三个词组组合的文献结果数