According to the Punnett square: B represents the dominant gene for blue feathers and b represents the recessive gene for red feathers. Two heterozygous birds have one offspring. What percent chance does it have for red feathers?

25% chance of having red feathers.

Explanation: Since Blue feathers is dominant while red feathers is recessive, a heterozygous bird will have a genotype of Bb. A cross between two heterozygous birds will produce four offsprings with the following possible genotypes of 1BB, 2Bb and 1bb. The birds having genotypes BB and Bb will manifest outwardly as blue feathers while the bird having the genotype bb will manifest outwardly as red feathers.

Since one out of the four offsprings have bb genotype, therefore the chance of having a red feathered bird is 1/4 x 100 = 25%

See attached punnet square for more information

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).   so the answer is a.