Answer:- 2,1
Explanations:- Water is 
and from it's formula it is clear that the ratio of H to O moles or atoms is 2:1 means two hydrogen atoms for each oxygen atom. No matter what amount of water we have, the ratio of H atoms to O atoms is always same.
Hence, the answer is 2,1.
The sun provides energy through nuclear fusion by fusing the atoms of hydrogen and helium in the suns core, so the answer is D
The answer would be:
Oceanic-Oceanic Convergent Plate
This is why:
When two oceanic plates collide, the heavier of the two would subduct or in other words, go under the other plate. When this happens, ocean trenches and volcanic arcs form. The trench forms at the point oceanic plate goes under the other plate. And above the other plate that goes over create volcanic arcs.
Parasite lives off the host so if the host dies, they are forced to look for another host. They can also leave its host if the parasite kills its host when it finds a new host, because if the parasite does not have a host its dies off.
Hope this can help explain
