If skin color were inherited in a simple dominant or recessive pattern, like seed color in pea plants. What would be the genotypes of dark- skinned parents that could produce fair-skinned children?

the genotypes of both parent would have been heterozygous for the trait.

Explanation:

In the simple dominant or recessive pattern as described by Gregor Mendel  in the year 1865 involving single gene inheritance. Illustrating this pattern using dark-skinned and fair-skinned people. Assuming dark-skinned to be dominant over fair skinned. the dark skinned parents if both are homozygous for dark skinned would not produce a fair-skinned child but if both are heterozygous for dark skinned, a fair skinned child can be produced. using D to indicte dark-skinned and d to indicate fair skinned, we have:

genotype       DD           x            DD

F1 genotype                 DD

phenotype             dark skinned

genotype              Dd            x           Dd

F1 genotype          DD      Dd                dd

phenotype         dark skinned and fair-skinned

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.