Susan's Search Costs Are $7 Per Search

Susan's search costs are $7 per search.She wants to buy a coat,and the lowest price she has found so far is $180.Susan thinks 25 percent of the stores charge $180 for this coat,50 percent charge $160,and the other 25 percent charge $150.Susan's optimal decision is to:

A) continue to search for a lower price since the expected benefit of an additional search is $7.50, which exceeds her per-unit search costs.
B) stop searching and purchase a coat for $180.
C) continue to search for a lower price since the expected benefit of an additional search is $10, which exceeds her per-unit search costs.
D) continue to search for a lower price since the expected benefit of an additional search is $17.50, which exceeds her per-unit search costs.