Genetic Diseases in Humans Are Usually Rare and Recessive

Genetic diseases in humans are usually rare and recessive. Why are the frequencies of alleles that cause rare, recessive diseases (or other recessive traits, for that matter) generally much higher than the frequency of the diseases (or traits) themselves?

A) Diseases caused by dominant alleles are generally lethal, and so most diseases are caused by recessive alleles.
B) Most of the rare, recessive alleles within the population are "hidden" within heterozygote carriers, which do not manifest the disease (or express the trait) .
C) Mutation rates are very low, and so recessive alleles are rare, which results in few recessive disease traits.
D) Most recessive mutations are lethal; as a result there are few recessive diseases.
E) Detrimental alleles are always being removed from a population due to natural selection.