<p>A number of scientists [(A)have begun] to speculate [(B)whether] life [(C)actuallly began] as crystals of clay rather [(D)than] as organic molecules</p>
<p>the answer is E
why is it E?
shouldn't it be A since a number of scientists is singular?</p>
<p>A number of scientists is plural.</p>
<p>can you tell me why</p>
<p>A number of scientists.
one scientist can't possibly be "a number of scientists"</p>
<p>It is different however, if it was "each".
Each of the scientists <- would be singular.</p>
<p>When there is an ambiguous subject, the number of the verb is dependent on the prepositional phrase after the subject. You've probably been taught to disregard prepositional phrases, and you should in most cases; this is one of the only exceptions. </p>
<p>A number has/have begun</p>
<p>A number of scientists have begun</p>