If a parent with AB blood and a parent with
O blood have kids, what percent of their
children will have each blood type?

O blood is a recessive trait, so none of the children will have O blood. The genes for either type A or Type B will be determined by the egg/sperm being fertilized with the reproductive cell of the other parent. the probability of receiving either of the gene versions is 1/2, so half of the children will have A blood and the other half will have B blood

since there are no options posted i'll give you a few examples.

a dolphin's flipper, bird's wing, cat's leg.