It’s necessary to be prepared for a job interview. the answer ready will be of great he

It’s necessary to be prepared for a job interview.              the answer ready will be of great help

A.To have had

B.Having had

C.Have

D.Having

答案及解析： D

解析：

考查非谓语动词。句中Having the answer ready为动名词短语作主语，句意：准备工作面试时有必要的，准备好回答是很有帮助的。