How do most autosomal recessive alleles that lead to lethal diseases persist in human populations?

Choose one:
A. The environment plays a large role in determining whether the gene is expressed.
B. The disease-causing allele can “hide” in the heterozygous condition.
C. These diseases usually take effect later in life after people have had children.
D. These diseases only affect individuals who are XY.

B. The disease-causing allele can “hide” in the heterozygous condition.