When using the high$-$low method, the numerator of the equation that determines the slope is the $\_\_\_\_\_\_\_\_.$

Question $5$ options:

$1)$

difference between the positive and negative values of dependent and independent variables

$2)$

difference between the fixed cost and variable cost associated with the cost driver

$3)$

difference between the high and low observations of the cost driver

$4)$

difference between the costs associated with highest and lowest observations of the cost driver