<p>Hmm, SparkNotes. I don’t actually believe that the second part is made into a dependent clause by the word “but.” It is a coordinating conjunction. Dependent clauses tend to be introduced by subordinating conjunctions or relative pronouns (maybe other forms).</p>
<p>I’d put this into the “can’t really tell” category of SAT practice examples. It would help if there were a closely related example from a real SAT or the SAT question service. In my experience, the SAT writers are absolute sticklers for the rules they observe. They are not very insistent on the rules they don’t personally observe, as the discussion of the use of “his” in crazybandit’s post #5 shows.</p>
<p>I believe that silverturtle and I would both say that you can get this one “wrong” (if A indeed is right) and still score an 800 on the writing section.</p>