Give the single best correct answer

Select one:

a. If there are no non-negativity constraints in a spreadsheet solver, then it is not possible to get an answer

b. The method of level curves can not be used to solve linear programming problems because curves are non-linear

c. In a linear programming (LP) problem, either the objective function has to be linear or the constraints have to be linear, but they don't all have to be linear d. Sometimes, identically the same problem can be framed in two different but equivalent ways, and the same person will give a different answer

e. If there are no non-negativity constraints in a spreadsheet solver, then if it is possible to get an answer, then all values will be negative

f. If two different linear programming problems have the same objective function and the same constraints but one problem seeks to maximise the objective function while the other problem seeks to minimise the objective function, then the two problems must necessarily give different answers