I think it mite be d.....hope this helps!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
Concept of Conservation: Matter cannot be created or destroyed. Matter can only change forms!
Explanation:
conservation of matter - a fundamental principle of classical physics that matter cannot be created or destroyed in an isolated system
Answer:
replacing defective blood-making cells
Explanation:
I'd go with A, Nucleus. I hope this helps!