I believe the correct answer is C
The greenhouse effect is the trapping of a stars warmth in the lower atmosphere of a planet by gasses in the air trapping the energy. This is similar to what actual greenhouses do, where they trap the warmth and humidity of the air inside it so plants can flourish. Farm animals produce a huge amount of the greenhouse gasses required for our planet to trap the suns warmth.
The sentences that make sense are "Volatile liquids are flammable" and "Liquids burn easily."
<span>My pea plant has an unknown genotype for flowers, whether it has two dominant traits for white flowers (WW) or one dominant and one recessive (Ww) leading to white flowers; therefore I am doing a testcross in order to determine the genotype of my pea plant. The best plant to do this with is one that has a phenotype of purple flowers (ww) - that is, it is homozygous for the recessive trait.
If I use a homozygous recessive plant, I know exactly what its genotype is. I don't have to worry about whether it's got one or two dominant alleles; I know that at least half of my alleles are going to be the recessive w.
This makes identifying the offspring's genotype very simple. If I find that the offspring have at least some purple flowers among them, I know that my original plant had to be Ww; that is it had to have one dominant and one recessive allele for the flower color gene. If, however, all of the offspring are white flowers, I know that my original pea plant had both dominant alleles (WW).</span>
