<p>Astronomy is the study of celestial bodies in outer space, [especially their positions, dimensions, movements, and composition.]
A) typed above
C) especially studying their positions, dimensions, movements, and composition.
E) with special study of their positions, dimensions, movements, and including composition.</p>
<p>[correct answer:A]
Could someone explain why "A" is correct and why the others are not correct?
Also what is 'their' referring to? If you take out prep. phrase, shouldn't it be... Astronomy is the study..... especially THEIR....?</p>
<p>First both (C) and (E), whether or not they are grammatically correct, are awkward. That’s often reason enough to eliminate them. But you’re looking for the grammarian’s answer.</p>
<p>“Their” refers to “celestial bodies”. The antecedent is not terribly confusing because it’s the only plural noun in the preceding clause.</p>
<p>(C) is wrong because the antecedent of the gerund “studying” is missing. Presumably it is “astronomers”. They do the studying. Also the presence of both “study” and “studying” in the same sentence is not particularly good writing even if you were to fix the antecedent problem somehow.</p>
<p>(E) repeats “study”. That’s reason enough to dismiss it. Also “with special study of” is equivalent to “especially”. Think of that as “redundant” phrasing – i.e. just say “especially”. That gets you back to (A). In other words, if (E) is right grammatically, then (A), which is simpler, is better.</p>