Consider a market for used computer printers, where buyers value good ones at $1,000 and bad ones at $760. Sellers value good ones at $910 and bad printers at $690. Sellers can attach a warranty at cost of $20 per month for good ones and $45 for bad ones. What is the minimum number of month necessary in order for the seller of good printers to be able to signal her type?

Group of answer choices

5

6

9

11