C. But be aware it increases in the third shell by 1 from left to right
C. How can we make an artificial heart
The population is exceeding what the Earth's resources can supply we hardly have enough food for certain countries and also to places like China who do not believe in global warming or anything of that sort pollute the air consistently which is why they've been in a fog for the past few weeks I believe and not only that if it continues we will use up all of our natural resources the more people the more resources
I am pretty sure the answer is D (combination)
