A metaphor compares one thing to annother thing, like the example you used. The answer is metaphor.
I'd say "but" is a transition word here.
It would be Verb, verb explains an action word. D.
Answer:
Choose C, but be prepared to see the answer as B. I'd argue a bit, but not much. It is pretty exaggerated, but it is also compared to something.
Explanation:
There is no part standing for the whole or no whole standing for a part. Not synecdoche.
Not a simile. No like or as.
Maybe a metaphor if you stretch it. Love is compared to a gold mine or the riches of the East.
I think the best answer is a hyperbole. It is an exaggerated comparison.
Answer: C
But don't be surprised if the answer turns out to be B.