Reptile scales! Or, more specifically, reptiles descended from dinosaurs.
Answer: 3 Sub classes wingless insects known as apterygota and winged insects known as pterygota
Explanation:
C) near the mouth
- - -
The mouth is where the river flows into another body of water and there is least oxygen here. The river slows down here and that decreases dissolve oxygen.
They are both made up of subunits called nucleotides, which include a sugar, a phosphate group, and a nitrogen base.