<p>The Official SAT Question of the Day</p>
<p>Part of the following sentence is underlined; beneath the sentence are five ways of phrasing the underlined material. Select the option that produces the best sentence. If you think the original phrasing produces a better sentence than any of the alternatives, select choice A.</p>
<p>The moose and the wapiti are the largest members of the deer family, each of them are found in North America, Europe, and Asia.</p>
<p>A. family, each of them are
B. family, both are
C. family, which are
D. family and are both
E. family and each are</p>
<p>I didn't understand the explanation:
It avoids the errors of the original by eliminating the extra subject, "each," and by avoiding subject-verb disagreement.</p>