<p>The answer is A: the original sentence is grammatically correct. The correct construction is “Just as . . . , so. . . .”</p>
<p>The “so” in this context means “in the same way,” or “in the way described previously” (or some variant of this). The “as” in this context means “in the manner (that).” Both words are used as adverbs here.</p>
<p>Here are examples of each individual usage:
As:
a. “The man did as promised.” “The man did in the manner promised.”
b. “He followed through as negotiated.” “He following through in the manner negotiated.” </p>
<p>So:
a. “I don’t think so.” “I don’t think in the way suggested.”
b. “I took a sip, and so did he.” “I took a sip, and he did (too) in the same way.”</p>
<p>Here is the original sentence:
Here is my breakdown:
The translation seems kind of redundant, sure, and, consequently, “so” does not NEED to be there. The construction would be fine without the “so,” but you can add it to clarify. Another variant would be, “Just as . . . , so. . . .” Neither “as” nor “so” are conjunctions (e.g., “because,” “and”), so it makes sense to use both two modify their two, respective clauses.</p>
<p>NOTE: If all of this seems too complex, just memorize the construction “just as…so.” I kind of over-killed it on the explanation anyway. Also, Barron’s is not a good book to study from. Just stick to the Official SAT Study guide–it is more accurate (obviously, since it is made by the College Board) and, in turn, has practice tests that are much more helpful.</p>
<p>(B) is wrong because there are two verbs (two was’s) in the clause, which makes no sense.
(C) is wrong because there is no verb in the clause. It is also lousy in other respects.
(D) uses the same correct construction as the original sentence, but the rest sounds awkward.
(E) is wrong because the conjunction “and” is unnecessary and breaks the connect between the two clauses (it’s used to start a new idea), and it uses “such,” which is not the same as “so.”</p>