The mass number is the sum of the number of protons and number of neutrons the atom has.
So, we can write the equation as:
x + 20 = 40
x = 20 neutrons.
Good roots, sunlight, and a stable base
It was the trip that Charles Darwin went on in attempt to find the answer of how animals got on earth in the first place and how they changed over time. This later on helped him discover evolution and natural selection. The most significant find on this voyage was that he found that different types of finches evolved to the food around them. Smaller beaks meant the finch ate more small nutrients but larger beaks meant the finch ate more harder prey such as fish and worms.
I believe the answer would be D. They create a temporary higher crest
I think it's D because I suppose that 'all its chromosomes' equals diploid