earth, wind ,fire ,and air
D. Cholinergic antagonists
<u>Answer:</u>
<em>A constant is something whose value cannot be changed and is used for comparison purpose. </em>
<u>Explanation:</u>
The controlled variable is a type of variable whose value is kept constant during the experiment to get the desired or expected result. The difference between constant and a control variable is that the constant can never be changed.
However, the value of control variable can be changed but is kept constant with a purpose in an experiment to get the data. The controlled variable in a battery can be the multi meter that should be used for all the batteries.
The organ that living things such as fish use to extract dissolved oxygen from water are the gills. As land animals and humans don't have gills, we can't breath underwater and take in the oxygen from that source.
