Final answer:
The prepositions are 'at,' 'under,' 'near,' and 'from.' The four letters that are always vowels are 'a,' 'e,' 'i,' and 'o,' which are to be underlined in any given word to identify the vowels.
Step-by-step explanation:
The words that are prepositions from the provided options are at, under, near, and from. Prepositions are words that link nouns, pronouns, or phrases to other words within a sentence and usually indicate the temporal, spatial, or logical relationship of its object to the rest of the sentence as in "the man on the platform," "she arrived after dinner," "what did you do it for?" Therefore, the correct choices are A) at, C) under, D) near, and E) from.
For the fill-in-the-blank exercise that involves vowels, the four letters that are always vowels are a, e, i, and o. Underlining each vowel letter demonstrates understanding of this concept. For example, in the word 'constant', the vowel letters that would be underlined are 'o' and 'a'.