Related to the Economics in Practice on Page 51: the Amazon

Related to the Economics in Practice on page 51: The Amazon Kindle and the electronic textbooks available for the Kindle are complementary goods. Electronic textbooks and traditional, hard-copy textbooks are substitute products. If the price of electronic textbooks for the Kindle decreases,

A) demand for the Kindle increases, demand for electronic textbooks increases, and demand for traditional, hard-copy textbooks decreases.
B) the quantity of Kindles demanded increases, demand for electronic textbooks increases, and the quantity of traditional, hard-copy textbooks demanded decreases.
C) demand for the Kindle decreases, the quantity of electronic textbooks demanded increases, and demand for traditional, hard-copy textbooks decreases.
D) demand for the Kindle increases, the quantity of electronic textbooks demanded increases, and demand for traditional, hard-copy textbooks decreases.