Answer:
The correct answer is option A.
Step-by-step explanation:
Economies of scale refers to the situation when firms are able to reduce the average cost of production by expanding their business. Or in other words, when the average cost of production gets reduced with increase in output level, it is called economies of scale.
The firms in the market for natural gas are able to earn high profits in the long run because of economies of scale.
The fixed costs in the short run is high and often unprofitable, this discourages potential firms to join the market.