Meiosis. Sexual recombination. Crossing over. Independent assortment. Mutations.
The two MAIN sources would be genetic(sexual) recombination and mutations. Mutations allow for genetic variation, while genetic recombination allows for genetic shuffling. :)
The answer is true because walking does not affect the environment
The correct answer is option B
The fishes that live in the shallow water along the sea floor needs a flattened shape and eyes on the dorsal side because they need to see above and have least possibility that the eyes will be required to see downwards as they lie at the sea floor.
They have tail for protection and flattened body for easy swimming.
Example: Stingray.