Suppose we solve a maximization integer programming problem twice: first with all required integer and non-integer const

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Suppose we solve a maximization integer programming problem
twice: first with all required integer and non-integer constraints,
and second by dropping the integer requirements (i.e., treating all
decision variables to be continuous). Which of the following
statement(s) will hold?
A. The second solution is an upper bound on the first
solution
B. The optimal objective function values of the two solutions are
always equal
C. Excel Solver will not be able to find a solution for the second
problem
D. The optimal objective function value of the first solution is
always more than that of the second solution E. None of the
above