单选题 If D represents checkable deposits, R represents reserves and r represents the required reserve ratio, the equation that expresses the relationships among the variables is:

A. D=R/r.
B. R=D/r.
C. r=D/R.

【正确答案】 A

【答案解析】The quantity of checkable deposits (D) that can be supported with the available reserves (R) is equal to R/r, where r is the required reserve ratio.