As Charles Darwin observed, natural selection operates whenever individuals of one genetic composition are better at reproducing than that of others.
这里是比较individuals of 一组 与 indivuduals of 另一组,所以要用复数those
再者the other指两者直接,another指三者之间
A. that of others
B. the other
C. another
D. those of another (D)
E. that of the next