Answer:
C
Explanation:
The principle of superposition states that the oldest sedimentary rock units are at the bottom, and the youngest are at the top. Based on this, layer C is oldest, followed by B and A. So the full sequence of events is as follows: Layer C formed.
Vertebrates have back bones or spines that give there body support.
The effect of a neurotransmitter is based on the properties of the receptor more than the neurotransmitter.
On average 30 feet or 9 meters