Both sentences A and B are capitalized correctly:
Only one solution is possible: We must cut our expenses.
Only one solution is possible: we must cut our expenses.
The first word of both sentences (only) must always be capitalized since it is placed at the beginning.
On the other hand, if the sentence following the colon is dependent (it is incomplete), its first word should not be capitalized. For example:
"I have to buy three things: apples, oranges and bananas."
Regarding capitalization in independent clauses following a colon (such as the one given in the example), it is subject to the citation style the writer is following (APA, MLA, etc). While some styles recommend capitalization of the first word of the sentence, some others do not.
Figurative language is most common in poetry, but poetry does not always explore thought in a concise way, more often it tried to convey a feeling or an impression than treats the subject in detail.
Therefore I would choose a "novel" - it can use figurative language (unlike exploratory essay), but it also deals with ideas and thought is a profound, comprehensive way (but note that some poems will also do that!)
<h2>By using military statistics</h2>