C. hydrogen accreted onto a white dwarf from a close companion rapidly fuses to helium, releasing a large amount of energy.
The accreted material, composed mainly of hydrogen, is compacted on the surface of the white dwarf due to the intense gravitational force on that place. As material accumulates, The white dwarf becomes increasingly hot, until it reaches the critical temperature for ignition of nuclear fusion.
When rain falls on the land, it either seeps into the ground or becomes runoff, which flows downhill into rivers and lakes.
Answer:
The value is 
Explanation:
From the question we are told that
The horizontal speed is 
The horizontal distance is 
Generally the time taken by the hot magma in air before landing is mathematically represented as

=> 
=> 
Generally the initial vertical velocity of the magma when it was lunched is

Then the final velocity of the magma when it hits the ground is mathematically represented s

Here the negative sign mean that the direction of the velocity is towards the negative y -axis
So

=> 
The correct answer is (a.) Hydra. Hydra is not a dwarf planet, instead, it is the moon of the dwarf planet, Pluto. There are only four accepted dwarf planets by the International Astronomical Union which were the Haumea, Pluto, Eris, and Makemake.