Which of the following is true of the relationship between average and marginal costs? If marginal cost is greater than average cost, then average cost is increasing. If marginal cost is greater than average cost, then average cost is decreasing. If marginal cost is lower than average cost, then fued cost is decreasing. If marginal cost is lower than merage cost, then murginal cost is decreasing. If marginal cost is greater than average cost, then marginal cost is decreasing.