Number 1 is a phrase and number 2 is clause 3 is also a clause and A clause is a group of words that consists of a subject and a verb. ... A phrase is a group of words that does not consist of a subject and a verb.
Answer:
Guts, known as oesophagus
Group of stars.
An appositive or appositive phrase renames a noun or pronoun that is right beside, specifically after, it. It is usually used to provide additional information, like a definition or clarification. In this sentence, "group of stars" is defining "constellations" making it the appositive phrase.