What is the objective function of coefficient for an artificial variable is?

What is the objective function of coefficient for an artificial variable is? For maximization LPP, the objective function coefficient for an artificial variable is(b)-M, (a) +M. (c) +1, (d) zero.

For maximization LPP, the objective function coefficient for an artificial variable is(b)-M, (a) +M. (c) +1, (d) zero.
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