Is the following sentence a sentence beginning with a prepositional phrase? “Against the wall, I sat curled up in a ball like an armadillo, as a stream of tears ran down my face.”

Yes this is a prepositional phrase!

Explanation:

Common prepositional phrase examples include about, after, at, before, behind, by, during, for, from, in, of, over, past, to, under, up, and with. These are words that are used in the prepositional phrases.

i also think the correct answer here would be b.

sonnet 130 follows the typical rhyme scheme of the form abab cdcd efef gg and is composed in iambic pentameter,a type of a poetic metre based on five pairs of metrically weak/strong syllabic positions.the first line exemplifies iambic pentameter.