One feature of （） is that it is possible to arrange for a single message to be sent to a large number of other users simultaneously.

A.Fax

B.IP telephone

C.Data Processing

D.E-mail

下列物质与偏头痛的关系最密切的是：（）

A.5－HT

B.儿茶酚胺

C.前列环素

D.阿片物质