you should say thank you when receiving something

you should say thank you when receiving something
you should say thank you when （ ）something
A.receive B.you received C.to receive D.receiving
when+分词构成的省略结构是什么?这题要是换一种答案是什么

when+【V-ing】=when+主语+V语境时态,典型地省略相同逻辑主语.
when receiving=when you receive（前面有should,这里用一般现在时态）