When you're given a point and the slope of a line, it is often easiest to write its equation in point-slope form.
This is
, where 
is the ordered pair for the point you are given and m is the slope.
Here, you would write
. Then, you simplify to get to slope-intercept form, which is 
, where b is the y-intercept.
The correct answer is A.
This is
Here, you would write
The correct answer is A.