y-intercept is -3 so it must pass the vertical line -3.
Now start from point (0,-3) and rise up by 3, then go right by 1 since the slope is 3/1 or 3.
It should look like this:
No matter the number of times you rolled the dice, the probability of getting a number is always 1/6. But here we can choose 4 numbers ( 1 to 4) hence the probability P( 1 or 2 or 3 or 4) = 4/6 2/3 = 0.6667 = 66.67% (A)