Answer:
When ATC curve is decreasing, we know that the MC curve is
below the ATC curve, and when the ATC curve is increasing, we know that MC is above the ATC curve
Explanation:
ATC refers to average total cost and MC refers to marginal cost, these both curve derive from total cost when MC is below ATC curve it shows that MC is less than ATC at that point ATC is falling.
Likewise, when MC is above ATC curve it shows MC is grater than ATC curve and at that point ATC is rising.
furthermore, when MC is equal to ATC at that point ATC is at minimum point.
The answer to your question would be A - a maxillary labial frenum, this part of lip tissue is responsible for diasetemic teeth - anterior teeth which are being too close to the maxillary labial frenum and which are therefore creating a gap between the front teeth.