A grocer buys bananas from a wholesaler at $1.00/lb and sells them for $1.30/lb. At the end of the week, if there are any unsold bananas, the grocer must pay $0.20/lb to ship the bananas to a food bank. During the week, if the grocer runs out of bananas, there is a $0.10/lb goodwill penalty as customers are less likely to shop at the store in the future. What is the critical ratio?
a) 0.25
b) 0.33
c) 0.50
d) 0.75