Final answer:
Options 3) b, 5) c, 7) d, and 8) p represent consonants; these letters help create sounds in English with a closed or partially closed vocal tract.
Step-by-step explanation:
In English, there are both consonants and vowels. The consonants in the choices given to you are b, c, d, and p. Meanwhile, a, e, and o are always vowels. Therefore, options 3) b, 5) c, 7) d, and 8) p represent consonants.
Of these, options 3) b and 7) d are specifically mentioned as consonant sounds in your references, corresponding to consonant sounds [b] and [d], respectively. Consonants are letters that are not vowels and they are used in the English language to create various sounds that are articulated with a closed or partially closed vocal tract.