小林学习还是比较认真的，但他有个毛病，遇到困难就怀疑自己的能力。请你从下面选一句最适合的话，送给他[ ]

A．不满是向上的车轮                             

B．千里之行，始于足下

C．点燃自信之灯，你定会发现自己有惊人之处       

D．少壮不努力，老大徒伤悲

An analyst does research about borrowing funds to purchase bonds. The sale of a security with a commitment by the seller to buy the same security back from the purchaser at a specified price at a designated future date is best described as:（）

A. margin buying.

B. negotiable CDs.

C. a repurchase agreement.