<li>(Introducing) new ideas and replacing )old ones) (is) always a highly controversial matter, (especially when) there is already tension between an older and younger generation. (No error)</li>
</ol>
<p>I’ll reveal the answer later. The sentence is weird.</p>
<li>A. What was noteworthy about this was that it was then possible for people to use elevators, not just freight.
D This development was noteworthy because elevators could now be used for people as well as for freight.
A 0r D. Why?</li>
</ol>
<p>First one, according to what you typed has no error. </p>
<p>Second one is D because it is the most clear and fluid sentence. Also when putting it in context with the rest of the passage it makes the most sense.</p>
<p>"(Introducing) new ideas and replacing )old ones) (is) always a highly controversial matter"</p>
<p>Look at this statement closely.</p>
<p>If you were to insert "are" instead of "is" then the word "matter" would have to be plural (matters). However because "matter" stays as a singular noun, it indicates that "Introducing new ideas and replacing old ones" is a single event, a single entity.</p>
<p>Example:</p>
<p>CORRECT: Wasteful spending is a highly controversial matter
INCORRECT: Wasteful spending are a highly controversial matter</p>
<p>yea^, <strong><em>? what's the rule? Kevzor I think maybe the question above deals with an idea. But nevertheless to say, the SAT is *</em></strong>ed up</p>