Dear xql:

In response to your inquiry, I don't think any of the answers is right.
Answer A is best choice, but it is informal.  Most Americans would say,
"Electricity is to agriculture as blood is to the body."  (We wouldn't
say "the agriculture," just "agriculture.")  "As" is used in analogies
to mean "in the same way that," as in "Red is to apples as yellow is to
bananas."

Actually, the analogy is a bit odd, since you can have agriculture
without electricity, but you can't have a human body without blood.

Hope this helps.

Richard Veit
University of North Carolina at Wilmington
_________________________________________________

xql wrote:

>Hello,everyone.
>I'm a chinese student.I came across a question as follows:
>
>Electricity is to the agriculture _____ blood is to the body.
>A)like
>B)that
>C)which
>D)what
 >
>The answer is C),and I don't know why.Is B) right?
>Thanks .