The relation between MC and AVC are as follows:
1. When MC <AVC, AVC falls with increase in the output.
2 When MC=AVC, i.e. when MC and AVC curves intersect each other at point B), AVC is constant and at its minimum point.
3. When MC > AVC, AVC rises with increase in output.
4. Thereafter, both AVC and MC rise, but MC increases at a faster rate as compared to AVC. As a result, MC curve is steeper as compared to AVC curve.