<p>In a 1 or 2 year old copy of the blue book, I found this question, and was having trouble with it:</p>
<p>By virtue of (A) its size and supersensitive electronics, mordern radio telescopes are able to gather more waves and (B) discriminate among (C) them with greater preceision (D) than earlier versions.</p>
<p>(A) its
(B) discriminate among
(C) them
(D) than</p>
<p>Why is (A) the right answer? What is the error in the sentence, and what word should it be replaced by? I chose (E) no answer for this.</p>
<p>“its” is a possessive pronoun that is supposed to refer to “modern radio telescopes,” but one is singular (its) while the other is plural (telescopes). “Its” must be “their”: </p>
<p>INCORRECT: By virtue of its size and super-sensitive electronics, modern radio telescopes are . . . </p>
<p>CORRECT: By virtue of their size and super-sensitive electronics, modern radio telescopes are . . .
CORRECT: By virtue of its size and super-sensitive electronics, a modern radio telescope is . . .
CORRECT: Modern radio telescopes are . . . by virtue of their size and super-sensitive electronics.</p>