How is an LP problem changed into an ILP problem?

a. by adding constraints that the decision variables be non-negative.
b. by adding integrality conditions.
c. by adding discontinuity constraints.
d. by making the RHS values integer.

Option B

by adding integrality conditions.

Explanation:

To change a linear Programming problem to an Integral linear programming model, you need to add integrality conditions.

The main difference between LP and ILP is that the in integer linear programming, the he solution to the LP must be restricted to integers (whole numbers).  

This defines the integrality condition of ILP problems, making option B the correct answer