Which include statement must you use to define and use input file streams

The expression d *= 4 is an abbreviation for:

a) d = 4d b) d * 4 = d c) d = d * 4 d) d * d = 4

What syntax would a Vim user choose if they wanted to perform a search-and-replace operation on an entire document?

A. :r/"string"/"string"/g B. %r/"string"/"string"/g C. :s/"string"/"string"/g D. %s/"string"/"string"/g