<span>False. A condition in which gametes are the same size and shape is isogamy. </span>
I would say that the answer is D.
Birds, unlike mammals, do not have separate exits for urine and feces. Both waste products are eliminated simultaneously through the cloaca. While mammals excrete nitrogenous wastes mostly in the form of urea, birds convert it to uric acid or guanine, which reduces water loss in comparison.
Dominant' traits will actually disappear faster if they are disadvantageous.
Think about it: if everyone who has even a single copy of a particular allele is at a disadvantage (manifests the phenotype, in this case six fingers), then even single copies are selected against.
In the case of recessive traits, selection occurs only against homozygous carriers, who may be very rare if the allele itself is rare.
A concrete example would be something like Tay-Sachs disease. If the allele that causes this were dominant, every carrier would die before adulthood, and it would occur only as a very rare de novo mutation. But because it is recessive, it persists for now; heterozygous carriers have no disadvantage.
