Question

1. which group of organisms evolved first?

reptiles
mammals
fish
amphibians

Explanation:

Based on evolutionary timelines, fish appeared in the fossil record approximately 530 million years ago, which is earlier than amphibians (~370 million years ago), reptiles (~310 million years ago), and mammals (~200 million years ago). Fish were the first vertebrates to evolve and colonize aquatic environments, with other groups branching off later in evolutionary history.

Answer:

fish