Answer:
The correct option is A. they evolved from land mammals.
Explanation:
Evolution can be described as a process through which organisms in a species change over a period of time due to the natural selection of the environment. Those organisms that have many similarities in their functions or structures are considered closer to one another and have the same common ancestors.
The properties mentioned in the question about cetaceans resembles the properties of land mammals. For example, cetaceans lack gills and breathe air. Land mammals also do not have gills and need to respire for living. The cetaceans have fin bones which are similar to the limb bones in the land mammals. Hence, these observations show that cetaceas have evolved from land mammals.
Answer: it is to prepare the six-carbon ring for cleavage
pls mark as brainliest. thank you
Water was the only type of life on the planet for hundreds of million of years
