Question

when cnidarians alternate between forms, they are select answer as juveniles and select answer as adults.

Explanation:

Cnidarians (like jellyfish, corals) have a life cycle with alternation of generations (or forms). The juvenile (or larval - like) mobile form is the medusa? No, wait, actually, the polyp is often the sessile (attached) form, and medusa is the free - swimming form. Wait, correction: In cnidarian alternation of generations, the asexual stage (often juvenile - like in terms of development) is the polyp (sessile, attached, can reproduce asexually), and the sexual stage (adult - like for sexual reproduction) is the medusa (free - swimming). Wait, some sources say that in the life cycle, the polyp is the asexual phase (can be considered as a juvenile - like stage in terms of the cycle's progression) and medusa is the sexual phase (adult for sexual reproduction). So when cnidarians alternate between forms, they are polyps as juveniles (or in the asexual, often more "juvenile - stage" part of the cycle) and medusae as adults (sexual, mobile stage for reproduction).

Answer:

First "Select answer" dropdown: polyps
Second "Select answer" dropdown: medusae