instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
A diploid cell is a cell with two chromosomes.
answer:
What kind of cell is a cell with two chromosomes?

question:
The main advantage of urea is its very low toxicity.
answer:
The main advantage of urea is its very low what?

question:
A collapsing nebula leads to nuclear fusion process.
answer:
A collapsing nebula leads to what process?