When MC is rising,AVC

A) must be rising.
B) must be falling.
C) may be falling or rising.
D) will remain constant.

When MC is rising, it means that the additional cost of producing one more unit of output is increasing. This could be due to factors like scarcity of resources, increasing marginal utility from these resources, or increasing costs of production processes. However, the impact of rising MC on AVC depends on how AVC is changing relative to MC. If AVC is rising at a faster rate than MC, it means that the average cost of producing each unit is also increasing at a faster rate, and hence, AVC will be rising. On the other hand, if AVC is rising at a slower rate than MC, it means that the additional cost of producing each unit is not having a big impact on average cost, and hence, AVC may be falling even as MC is rising. Therefore, the correct choice is C, which says that AVC may be falling or rising depending on its relationship with MC.