关于OG中的一道题

In recent years cattle breeders have increasely used crossbreeding, in part that their streers should acquire certain characteristics and partly because crossbreeding is said to provide hybird vigor.

c. partly because of their steers acquiring certain charateristics in their steers

e. partly to acquire certain charateristics in their steers

看了注解 还是不明白为什么不选c.请各位讲解

你把这句话翻译成中文就明白了。

养牛人开始使用杂交育种，一方面是因为小牛获得了特性，另一方面是因为杂交育种可以提供杂交优势。

有没有发现很别扭，好像是在说，因为小牛获得了特性，养牛人才开始使用杂交育种的。