When deciding on output levels, members of a cartel a. set their output where mr=mc b. produce the same level of output as if they were in a competitive market c. take into account the impact of changes on members' profits d. act as if they were monopolies.

Option(D) is correct.

Explanation:

Correct option:  Act as if they were monopolies.

Cartel is a group of few firms that work towards the common goal. Because all the cartel members works together, that's why they act like a monopolies.

They decided to produce at a level where their combined marginal revenue is equal to the combined marginal cost.

Because they behave like a monopolist, so they sell lesser quantity at a higher prices than would be in a perfectly competitive market.