①"natural selection operates" 复数
②one...another...固定搭配

正如查尔斯·达尔文（Charles Darwin）所观察到的，只要有一个遗传组成的个体比另一个具有更好的繁殖能力，自然选择就会起作用。

individuals-->those
one genetic composition-->another

another的用法解释一下呗？

比较

比较两边的内容必须一致。

比较对象是individuals

better reproduce修饰individuals,说明比较对象是individuals

找准比较对象，根据“怎么样的individuals are better at reproducing 比 怎么样的individual"，是不同individuals之间的比较, 因此比的是 individuals of one genetic composition
那么than后面和其对应选择 ： those of another.
因为根据单复数原则 those指代 individuals； another指代 composition

individuals of one genetic composition are better at reproducing than individuals of another genetic composition

individuals——those
单数 that

[Note] (From Ron)
the comparison must be made between individuals of one genetic composition and individuals of another genetic composition. therefore, (a) and (e) are wrong because "that" is singular; we're supposed to be comparing individuals (plural).
(b) and (c) are wrong because "other"/"another" refers to another genetic composition

(b) and (c) are wrong because "other"/"another" refers to another genetic composition 比较是individuals

those和individual并列，genetic compositon和another并列

原句是individuals of one genetic composition, 所以比较个体们中的不同，individuals可以用those代替，只有D对。

individuals of one genetic composition=those of another

注意that／those单复数指代！！！！

找准比较对象，根据 reproducing判断，比的是 individuals of one genetic composition
那么than后面和其对应选择 ： those of another.
因为根据单复数原则 those指代 individuals； another指代 composition

[Note] (From Ron)
the comparison must be made between individuals of one genetic composition and individuals of another genetic composition. therefore, (a) and (e) are wrong because "that" is singular; we're supposed to be comparing individuals (plural).
(b) and (c) are wrong because "other"/"another" refers to another genetic composition

individuals of one genetic composition
所以后面的比较对象应该是复数形式，即不能使用that，而是使用those。

individuals 复数---用those指代；one genetic composition对应another