Answer:
C. Not to be built; unhappy
Step-by-step explanation:
The benevolent social planner is an individual who is a decision maker, who attempts to achieve the best. He is an all knowing, all powerful well intentioned decision maker that wants to maximize the economic well being of everyone in the society. In this case, the benevolent social planner is unhappy because the railway is not built. The rail way is not being built because the amount asked on the land is more than what Mariana is willing to pay.