In which maturity group would you find very young animals?

The correct choice identifies very young animals based on their developmental characteristics. In this context, the description of animals with red, porous bones and prominent buttons aligns with the physical traits of juvenile or younger animals. This group typically reflects their ongoing growth and skeletal development, which includes less calcification and a distinct texture and coloration of their bones.

As animals age, their bones become harder and denser, transitioning to a more mature form which is not characterized by the features mentioned in the correct choice. The focus on the presence of prominent buttons, or the growth plates, further indicates that the animals are in an early stage of life, transitioning from these juvenile characteristics to those associated with full maturity. Therefore, this classification of animals based on bone structure is essential in understanding the development and growth stages in animal science.