Consider the text and its central idea.

Informational Text:

People used to go to a music store to purchase their favorite song. They would drive to the store, select a compact disc (CD) by their artist of choice, and purchase the CD at the cash register. This method has been declining for years. Now music fans can shop on the Internet in virtual music stores. There, they can easily purchase and download songs and albums. This method has become so popular that over 50 percent of all music purchases are now done online. Millions of dollars worth of music are purchased on laptops, digital music players, and phones.

Central Idea:

Buying music online has become more popular than buying music at stores.

What supporting detail is most important to include in a summary of this text?

a)Stores use cash registers to record purchases.
b)People listened to and collected CDs (compact discs).
c)More than 50 percent of today’s music purchases are online sales.
d)Many people can access the Internet on their smartphones.