With ATMs, it is possible to retrieve cash from the bank at any time. One hundred years ago, one could only get cash from the bank during business hours, say, 9 am to 3 pm. The present availability of 24-hour service has arisen because:

A.government forced banks to become more convenient.

B.it was impossible to provide 24-hour service 100 years ago.

C.the cost of providing 24-hour service is much lower today.

D.flexibility was not valued 100 years ago.

正确答案：the cost of providing 24-hour service is much lower today.