“conceit” is best defined as a lengthy or extended
metaphor
symbol
image
hyperbole

The correct answer is A. A conceit is an extended metaphor, where the metaphor is used throughout the entire work. Furthermore, a conceit compares two very different things in order to highlight their hidden similarities. A famous conceit is that of John Donne's poem "The Flea." In this poem, he compares love to a flea. These two things are clearly quite dissimilar; however, over the course of the poem Donne makes the argument that love and a flea are not so different after all.