<span>Recruitment of motor units.
Altering frequency of the stimulation.</span>
Answer:
Hardness (H) is the resistance of a mineral to scratching. The degree of hardness is determined by observing the comparative ease or difficulty with which one mineral is scratched by another or by a steel tool.
Explanation:
https://www.britannica.com/science/mineral-chemical-compound/Hardness Hope this helps
The burning of Fossil fuels.Under natural conditions the release of carbon from fossil fuels occurs slowly, as they are subducted in the mantle and CO2 is released through volcanic activity.
By transfer through cellular respiration.