An investor opens a margin account with an initial deposit of $5000. He then purchases 300 shares of a stock at $30. His margin account has a maintenance margin requirement of 30 percent. Ignoring commissions and interest, the price at which the investor receives a margin call is closest to.（）

A. $14.26.

B. $18.72.

C. $19.05.

锅炉汽包内旋风分离器歪倒数个，引起汽包同侧蒸汽的含钠量升高，需要采取的措施是（）。

A.开大连排

B.定排一次

C.申清锅炉检修

D.改变锅炉运行工况