Science Citation Index-Expanded(SCI-E)数据库中，课题“两性聚电解质溶液的结构研究”，最佳检索式为

A、ts="study on the structure of polyampholyte solution";

B、ts=structure and ts="polyampholyte solution";

C、ts=structure or ts=polyampholyte solution;

D、ts=structure and ts=polyampholyte solution