I think one is carbon dioxide not sure what the other is
Bursa - A small sac that lubricates the area around a joint where friction is most likely to occur
ex. elbow, knee, or shoulder
Answer:
The answer is between a or b
but I strongly suggest the option a.
Evolution is the answer
The natural cause of acid rain is the <span>chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air.</span>
