Since we have two ordered pairs, we can find the slope by plugging them into (y2-y1)/(x2-x1) which translates to (3-(-6))/(-4-(-1))=9/-3=-3
Since the slope is -3, we have the equation y=-3x+b, but we don't know b. So we plug in values for x and y and solve for b.
-6=-3(-1)+b
-6=3+b
-9=b
So the y-intercept is -9 and the full equation is y=-3x-9 which means A is the only correct answer.
Hope this helped!