C , I think , Hope this helps
The correct answer is endorphins.
During strenuous exercise, the brain releases the neurotransmitter called endorphins. Endorphins are known as "feel good" chemicals that produce a feeling of euphoria, reduce anxiety and the ability to experience pain. Endorphins also produce a feeling of happiness and relaxation after an intense exercise session.
Mayan number system is a vigesimal system- that means with a base of 20:
the correct answer is: 20, the Mayan number system is based on the number 20.
This means that a number like 360 is expressed with "18 times 20".
Scientists suggest that number systems based on 10 are inspired by the number of fingers, and number systems based on 20 could be based on fingers counted twice: after the number 10, hands would be turned upside-down.
