They are practicing ________ now. You can wait here. [ ]

A. swimming

B. going swimming

C. to go swimming

D. to swim

某建设项目，固定资产投资额为3176.39万元，流动资金为436.56万元，项目投产期利润总额为845.84万元，达到设计能力的正常年份（生产期）的利润总额为1171.89万元，则项目正常年份的投资利润率是（）。

A．32.44%

B．31.23%

C．34.5%

D．33.15%