Consider the following linear programming model:
Maximize X12 + X2 + 3X3
Subject to:
X1 + X2 ? 3
X1 + X2 ? 1
X1, X2 ? 0
This problem violates which of the following assumptions?
A) Certainty
B) Proportionality
C) Divisibility
D) Linearity
E) Integrality