You are analyzing a human pedigree for a new disease and discover that the disease occurs with the same frequency in both sexes and that 25% of the children from two unaffected heterozygous parents have the disease. this disease is displaying inheritance.
a. autosomal recessive
b. autosomal dominant
c. sex-linked recessive
d. sex-linked dominant

The correct answer is A. autosomal recessive

Explanation:

In an autosomal disease, the mutation occurs in the autosomal chromosome, not in the sex chromosome. In autosomal recessive disease if both the defected allele from parent comes in the child then only the child would be affected by the disease. If the offspring have single defected allele than he is said to be a carrier.

So as the defect is not in sex chromosome the disease will occur in the same frequency in both the sexes and if parents are carriers which means they are not affected by disease than 25% offspring can have the disease because out of four offspring one can get both the defected allele, one from each parent. So the correct answer is A.