Answer: couplets, <span /> structure, inverting sentences
Part A:
A - Wind power is an underused resource that has the potential to provide the energy to power electricity for the entire country.
Part B:
Effective; the author acknowledges the counterclaim and explains the U.S. Department of Energy’s plan to increase the use of wind energy in the future.
A phrase that uses symbolism is;
B. Though the flowers were long dead, she kept them in the vase to remember him.
Purple host could be ambiguous, or not clear, because of the figure of speech and the double meanings. Purple host could be taken literally as a host with a skin pallor of purple. But it could also mean that the host is feeling proud, hence they use the color purple as symbolism. Also, it could mean one way or another. Hence, the answer is letter C.