Problem Solving (PS) | An author receives 10% of the publisher’s net receipts in royalties on

An author receives 10% of the publisher’s net receipts in royalties on the first 10,000 copies of the author’s book sold, 12% on the next 15,000 copies sold, and 15% on all copies sold thereafter. By what percent does the ratio of the royalty percentage to number of copies decrease from the first 10,000 copies to the next 15,000 copies?

(A) 2%
(B) 10%
(C) 15%
(D) 20%
(E) 25%

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