It is definitely not B nor D because those two have negative meanings. It can't be C because excessive means "beyond the usual", which has a slightly negative meaning.
The answer should be A, conversational.
<span>1) theme is the main idea or the message conveyed through a work. So a synonym for theme is plot message.
2) Each refers to a singular noun. So the following verb and pronoun must also be singular. The correct pronoun to be used in the blank space is his.
3)Possessive case indicates possession whereas nominative case just refers to the name. In the above sentence, the umbrella belongs to someone or someone possesses the umbrella. So both yours and mine are in the possessive case.</span>
D
Cornerstone for me is a 7/10 and the other one a for sure 9/10 :)