The answer would be C: 11. Here’s why:
The price of each pen at Store A would be 49¢. ($2.45 divided by 5).
The price of each pen from store B for each of the answer choices is as follows:
A: About 55¢
B: 50¢
C: About 45¢
D: About 42¢
If they want to beat Store A’s deal with the least amount of pens involved, then choice C is the best option.