The physician inserts a chest tube into a client to treat a pneumothorax. The tube is connected to water-seal drainage. The nurse can prevent chest tube air leaks by

A. keeping the chest drainage system below the level of the chest.
B. keeping the head of the bed slightly elevated.
C. checking and taping all connections.
D. checking patency of the chest tub

某农场养了一群马，有栗色马和白色马。已知栗色基因（B）对白色基因（b）呈完全显性，育种工作者从中选出一匹健状的栗色公马，试图根据毛色这一性状的遗传情况来决定是否让其作为种马。

为了在一个配种季节里快速完成这一鉴定工作，应该怎样配种？