请教大全补充250中第127题！

linlin2008

People who inherit the sickle cell anemia gene from only one parent seem to be resistant to malaria, an evolutionary advantage that may explain why a genetic condition so debilitating to many individuals has survived in the human population.

A)  seem to be resistant to malaria,
B)  seemingly are resistant to malaria,
C)  seem to be resistant to malaria and have
D)  seemingly are resistant to malaria and to have
E)  are, it seems, resistant to malaria, and they have

答案选A,搞不懂该句子结构，请各位高手赐教。

linlin2008

以下是引用boys在2005-5-4 8:37:00的发言： People (who inherit the sickle cell anemia gene from only one parent )seem to be resistant to malaria, an evolutionary advantage that may explain why a genetic condition so debilitating to many individuals has survived in the human population. 后面这个an evolutionary advantage 是指前面整个主句的情况产生情况.

thanks for your explanation.