The Decision Regarding How to Allocate Resources Between the Marcom

The decision regarding how to allocate resources between the marcom elements has been described as an "ill-structured" problem.What does this mean?

A) There is no solution to the problem.
B) It is difficult to define the problem.
C) There is no way of determining the mathematical optimum allocation among marcom elements.
D) There are solutions, but they are not acceptable.
E) There is no way to measure whether the solution chosen was the correct one.