A. Your leg jumping when it is hit by a reflex hammer
I think the only answer choice here that really makes sense is D
When animals undergo the process of cellular respiration, they release carbon dioxide into the atmosphere. And when animals die and start to decay aided by organisms called decomposers, carbon dioxide is also emitted into the atmosphere. When humans burn fossil fuels, carbon dioxide yet again enters the atmosphere.
<em>hope this helps ;)</em>
