The Owner of an Orange Grove Must Decide When to Pick

Multiple Choice

The owner of an orange grove must decide when to pick one variety of oranges. She can sell them for $18 a bushel if she sells them now, with each tree yielding an average of 7 bushels. The yield increases by half a bushel per week for the next 10 weeks, but the price per bushel decreases by $0.70 per bushel each week. When should the oranges be picked for maximum return? ​​

A) 10 weeks from now
B) 2 weeks from now
C) 7 weeks from now
D) 5 weeks from now
E) 6 weeks from now