I think it's lithosphere thanks for posting your questions on Brainly
Mechanical stress applied to bone increases osteoblast activity in bone tissue, and the removal of mechanical stress decreases osteoblast activity.
Explanation:
Osteoblasts are cells , that are produced in the bone marrow and are responsible for formation of bones and bone matrix.
Whenever a mechanical stress is applied on the bones , a series of reactions are triggered. As a result the activities of osteoblast increases to synthesize more and more bone matrix to provide strength.
Again on the other hand a decrease in mechanical causes a decrease in the activities of the osteoblasts.
Option C. Organisms were probably more complex during past eras.
I would say the alveoli. They are tiny air pockets in the lungs: this is where the diffusion of oxygen and carbon dioxide occurs.
Hope this helps! x
