Task: Question Answering
Input (English): Question: A used-book dealer sells paperback books at 3 times the dealer's cost and hardback books at 4 times the dealer's cost. Last week, the dealer sold a total of 130 books, each of which had cost the dealer $1. If the gross profit (sales revenue minus the dealer's cost) on the sale of all of these books was $300, how many of the books sold were paperbacks?

 Option A: 40

 Option B: 60

 Option C: 75

 Option D: 90

 Option E: 100
Output (English): Option D