At a price of $15 each, Marta buys 4 books per month. When the price increases to $20, Marta buys 3 books per month. Luz says that Marta's demand for books has decreased. Is Luz correct? Selected Answer: No, Luz is incorrect. Marta's quantity demanded has increased, but her demand has stayed the same. Answers: Yes, Luz is correct. No, Luz is incorrect. Marta's demand has increased. No, Luz is incorrect. Marta's quantity demanded has decreased, but her demand has stayed the same. No, Luz is incorrect. Marta's quantity demanded has increased, but her demand has stayed the same. No, Luz is incorrect. Marta's quantity demanded has decreased and her demand has increased.