CFAI Reading 15 Problem #6 - Economic Regulation

I am doing the practice problem for reading #15. Question # 6 asks whether the demand for money market funds will increase/decrease or remain constant after a regulation was put in place where a ceiling on interest rates paid by banks for certain Bank deposits.

The answer is increase, but I chose decrease. I cannot figure out why it would increase. Could someone provide an explanation as to the upward shift in demand?

Thank you in advance.