The prounoun "that" is used as a demonstrative pronoun in your sentence because it is used to demonstrate, or indicate something. In your sentence, that indicates which horse is your favorite.
Adjectives and Adverb phrases relate to prepositional phrases because if you remember what an adjective is, it describes a noun and then an adverb i believe can describe a verb, adjective, and other adverbs. Both adjective and adverb phrases contain prepositions, there fore relating them to prepositional phrases.... I hope this is what you were looking for and answered your question... :)
The answer is C. today. An iamb is used in various kinds of poetry but can also be a word that has a short first syllable and a longer second syllable. Or a word that has an unstressed first syllable and a stressed second syllable. In both case, only today fits those descriptions.
