<ol>
<li>Katarina could not be certain whether the voice she heard on the recording was her uncle or someone else who speaks with a heavy German accent.</li>
</ol>
<p>A) uncle or someone else
B) uncle or that of someone else
C) uncle's or someone else
D) uncle's or that of someone else
E) uncle's or someone else's</p>
<p>I couldn't choose between D and E. Aren't they both correct? The right answer is D. Could someone explain to me why E isn't right?</p>
<hr>
<ol>
<li>As the price of petroleum rises and concern about the environmental effects of petrochemicals mounted, the plastics industry is racing to create plastics not made from petroleum. No error</li>
</ol>
<p>The error in the sentence is mounted. Why is it "mounted"? Shouldn't is racing be changed to "has been racing"? PLEASE HELP!</p>