Why is the answer B?

Because it is the only equation that has a solution of (2, 1/2)

Plug in x = 2 and y = 1/2 into equation B and you will see that it works.  It does not work for D.

Note that if the question was asking for an equation that is parallel to line l, then the answer would be D, but that was not what they were asking.  So be careful answering some of the questions found on a math test.  In other words, you got tricked.

"GGWP, NO RE"
- the test maker