Oxygen diffuses from the to the where it enters red blood cells. A. Plasma membrane, Alveolus B. Artery, plasma membrane
C. Capillary, Artery
D. Alveolus, capillary

Iam not sure but to me it with be a or dsorry if i was late! hope this ! : )if you really want me to find out the answer that is correct tell me and i will do more research but the a or d makes sense to me.

Well,what i learned was that unlike many other  endothermic  reactions,  photosynthesis  does not absorb energy as heat. instead, during plants absorb energy from sunlight to turn carbon dioxide and water into oxygen and glucose, which is a type of sugar molecule. the energy is stored in the glucose molecules, ready to be used when needed. 

4. a b and cprocess included are: 1. reproduction, is as vital for an entire race to survive. it prolongs their generation onwards and offspring to the next centuries to pass by. 2. obtaining energy. in both humans and animals, even plants is a challenge because these creatures need to work in order to obtain these need resource from food –preys. 3. maintaining structure. for the living organisms to still exist they need to keep themselves intact. combating diseases and having nutrition. this is a by-product of having energy. 4. irritability. responding to stimulus5. excretion. able to dispose waste6. movement. being able to be in one place to another.7. growth. able to develop.8. death.