A way to offset the costs of these customers' defaults is to increase the interest rates of all customers, including those who are at almost no risk of defaulting on their lines of credit."
The concluding statement infer that the plan of increasing the interest rates of all customers, will lead to less default made by customers. The conclusion is flawed because:
A. Credit card companies could offset the costs of defaults by raising the fees they charge to merchants who accept credit cards.(Merchants are not specifically mentioned as one of the customer of the bank, it might broaden the existing scope or is a subpart of one, though irrelevant irrespective anything) (Incorrect)
B. Increasing the interest rates on high-risk cardholders is more likely to result in these cardholders defaulting. (Yes, if the customers default rate will increase the motive behind the whole plan will go in vain or completely opposite of expected results) (CORRECT)
C. Many credit card customers pay their bills in full each month, avoiding interest charges. (If majority of customer pay their bills on time, there wouldn't have any need of the plan from starting, but since they are defaulting payments the action is been considered)(Incorrect)
D. Increasing interest rates would not result in a higher monthly payment for high-risk cardholders.(Increasing interest rate will eventually make people pay up mount in order to pileup wholesome interest amount, so we can't exactly say there won't be any increase in monthly payment) (Out of scope)
E. Credit card companies have historically offered cards to high-risk customers at higher interest rates than those given to low-risk customers. (This statement infer the past but doesn't states out the result followed after the action has been taken place.) (Half Information)
Answer is B