Which statements are true of a white dwarf?
a. it has a red shell.
b. it is the result of the core collapse of a low-mass star that sheds its outer layers.
c. it emits massive amounts of light compared with other stars.
d. it strongly attracts all matter or energy that comes near it.
e. it cools down to become a black dwarf.

Option B, It is the result of the core collapse of a low-mass star that sheds its outer layers.

Explanation:

Stars which reaches the end of their evolution process becomes a white dwarf. The diameter of white dwarf is 0.01 times the diameter of sun but their masses are equivalent to each other. Stars at the stage of white dwarf are short of fuel as they have burned up its entire hydrogen. This leads to slowing down of fusion process followed by collapsing of stars on their own.

hence, only option B is correct

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.