Neurotransmitters, such as acetylcholine--the major neurotransmitter found in the human body, act over a short time and they are quickly removed from the synapse by enzymes (i.e. acetylcholinesterase which breaks down acetylcholine to acetyl-CoA and choline).
"(1) Human population growth reached 6.8 billion in 2010 and it continues to increase" is what led to the other <span>three, since all of these happen from human activity. </span>
Answer:
it's either A or D I believe. it's most likely D
Glucose and oxygen are the input molecules
