To find the slope, you can either use the slope equation:
(y2-y1) / (x2-x1)
{I would recommend you remember this because you'll need to know this in the future}
or,
Just count. A slope is rise over run, so you see how far up the slope goes from one point to the other, (1), and then you see how far sideways the slope goes (2).
Going right, the slope is naturally declining downwards, so it's a negative.
The answer is B. -1/2.