Slack
A)is the Difference Between the Left and Right Sides $\le$

Slack

A) is the difference between the left and right sides of a constraint.
B) is the amount by which the left side of a $\le$ constraint is smaller than the right side.
C) is the amount by which the left side of a $\ge$ constraint is larger than the right side.
D) exists for each variable in a linear programming problem.