When the tree is first planted, its carbon-14 is at 100%. what has to happen for that number to start changing?

Carbon is the building block of all organic molecules and is present in many other forms in the environment, and for this to happen it is called "carbon dating" therefore i would say that it has to experience the cycle in which you can easily find looking up c 14 dating!

the answer is option c.

explanation:

recycled water alludes to the water that being utilized again after it already  used for farming purposes.   this kind of water frequently contains pharmaceutical gathering due to the compound compost that is utilized for the plants is consumed into the water.

true. earthquakes are felt whenever there is a slip around a fault in the rocks below the earth. this reorientation of faults create sesmic waves and is known as earthquake, the severity of which is measured in richter scale. these are more prominent in hilly regions as the rocks usually form faults to balance the pressures on it.