What’s the answer really need help

A) 1.5

Step-by-step explanation:

You see, the slope is defined by y_2-y_1/x_2-x_1 so therefore if we look at 3 gallons of water and 4 gallons of water the y is length of string and x is water(gallons) so it's (4.5-3)/4-3=1.5/1= 1.5