Indicate the correct answer from the following types of the long run average cost curves on which the minimum average cost of production in long run can be determined.
1. Long run average cost curve under normal production function
2. Long run average cost curve under linearly homogeneous production function
3. Planning curve
4. Envelope curve

A. 1, 2 and 3

B. 2, 3 and 4

C. 1, 3 and 4

D. Both 2 and 4

Answer: Option C