I would say the correct answer is B. hyperbole.
Hyperbole is a figure of speech that authors use when they want to exaggerate things. So this 'vegetable love' cannot possibly grow larger than empires - the poem just wants to demonstrate the power and intensity of this love by using the figure of hyperbole. A paradox would include two completely opposite things, and <em>vast </em>and <em>slow </em>are not opposites.
The most accurate way to describe the excerpt is to choose the option - it is a dependent clause. This means that something needs to be added - you need to finish the sentence so that it becomes an independent clause, and not a subordinate one.
