<p>I can across this in the College Board's book:</p>
<p>The survey [showed] that most shopper who drive prefer the mall [more than] downtown stores [simply because] parking is [less difficult] at the mall.</p>
<p>Apparently the answer is (B) ,would anyone mind explaining Why? and if we were to correct it, how would it be then?</p>
<p>more than is already implied by the use of prefer. </p>
<p>prefer…more than … is thus redundant.</p>
<p>Exception…</p>
<p>If you are using the infinitive in the following way…</p>
<p>I prefer to drive rather than (to) walk.</p>
<p>… rather than is correct (the second to is optional).</p>
<p>Thanks YZamyatin</p>
<p>I taught it was an idiomatic error. It should be “prefer…to” or “prefer…over”</p>