Because an amino acid<span> cannot be </span><span>synthesized</span><span> by the organism, and it must be supplied in its diet.</span>
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.
