<p>kay, here.
1- Remarkable breakthroughs in gene research may lead to dramatic changes in medical (treatment, where it may be possible to create) drugs tailored to a patient's genetic makeup.</p>
<p>the correct answer is : (treatment by making it possible to create)
okay , what does (it) refers to ?
why does the choices d and e are wrong ?
d-treatment that makes it possible creating
e-treatment that makes possible creating?</p>
<p>You should take the sentence as a whole and you’ll surely notice that “by” is better.
“How do these breakthroughs can lead to dramatic change in medical treatment” simply “by making it possible…”</p>
<p>d) and e) don’t show that these new medical treatments are results of the remarkable breakthrough</p>
<p>And what does the “it” refer back to in the sentence if it is “by making it possible”? The answer is nothing. Yes, that can happen sometimes. The sentence has an idiom, “making it possible” which means creating the potential.</p>
<p>ahaaaa , wow. thank-you.</p>