so the equation is in slope-intercept form so
y=mx+b where m=slope (rise over run or rise/run) and b=y-intercpet or where the line crosses the y axis
so we look at the equation y=-1/3x+5
5=y intercept so the line will cross the y-axis at 5 so we can eliminate choice D
-1/3
remember that negative slopes will decent from left to right and positive slopes will acend from left to right so
the line will decend 1 unit for every 3 units it goes to the right so we can eliminate choices A , B, and D since they all go up from left to right
the answer is C