Question

Amphibians fish birds reptiles mammals insects which one is an odd one out
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Answer 1

Mammals

Step-by-step explanation:

Mammals are the odd ones out because they do not lay eggs. Unlike amphibians, fish, birds, reptiles, and insects, which do lay eggs.

Answer 2

Step-by-step explanation:

I think it's insects. All the rest have some sort of spinal structure. They are classified as vertebrates (meaning they have a spinal structure).