某平流沉淀池处理水量为10000m³/d，池长60m，宽为15m。若新建一个10000m³/d的沉淀池，宽为15m，要求进出水质相同，则新池的池长为（）m。

A．58.2

B．60.0

C．72.1

D．70.0

An at-the-money protective put position (comprised of owning the stock and buying a put) :()

A. protects against loss at any stock price below the strike price of the put. 

B. has limited profit potential when the stock price rises. 

C. returns any increase in the stock’s value, dollar for dollar, less the cost of the put.