If a Company Selects Either of Project 1 or Project $\le$

Multiple Choice

If a company selects either of Project 1 or Project 2 (or both) , then either Project 3 or Project 4 (or both) must also be selected. Which of the following constraints enforce this condition?

A) X₁ + X₂ $\le$ 2(X₃ + X₄)
B) X₁ + X₂ $\le$ X₃ + X₄
C) X₁ -X₃ = X₂ - X₄
D) X₁ + X₂ + X₃ + X₄ $\le$ 2