The answer is A.
Understanding the words in a poem will help the performer to better express the poem which results in a better reaction from the audience.
The answer to the question is D
the answer is<em> </em><em>is</em><em>.</em><em> </em>
Because there is written <em>one</em> <em>of</em><em> </em><em>the</em><em> </em>best new security systems. And it is singular.