Can you please help me answer the questions I was not able to figure out with explanations?

1) Suppose the supply of non-OPEC oil increases due to new petroleum discoveries in other countries. What happens to the price of oil on the world market?

A) Increases

B) Decreases

C) Remains the same

D) We do not have enough information to answer this question.

2) Why do firms tend to experience decreasing returns to scale at high levels of output?

A) Firms face more problems with coordinating tasks and communications among managers and workers at very high levels of output.

B) Government tax policy tends to discourage large-scale production operations.

C) Firms face fewer problems with inventory management and marketing as output reaches very high levels.

D) Firms tend to use more capital and less labor at higher levels of output

3) Which of the following industries are pure monopolies?

1. The only supplier of heating fuel in an isolated town

2. The only supplier of IBM notebook computers in town

3. The only supplier of digital cameras