控制采购的原材料及零部件的采购价格是企业生产过程中的重要环节。这说明企业采购具有（）功能。

A.生产成本控制

B.生产调度控制

C.产品质量控制

D.促进新产品开发

An analyst does research about margin transaction. An investor purchases common shares at $ 25 per share on margin and deposits just enough money to cover the 65% initial margin requirement. If the maintenance margin requirement is 30%, the share price below which the investor will first receive a margin call is closest to:（）

A. $11.54

B. $12.50

C. $19.70