Both of tim's parents have brown eyes, but tim has blue eyes. how is this possible? choose the best answer.

If Tim has blue eyes, then both of his parents are heterozygous for the brown eye trait.
Here would be the alleles:
BB-Homozygous Dominant for brown eyes
Bb-Heterozygous for brown eyes
bb-Homozygous Recessive for blue eyes

If you input the heterozygous allele for brown eyes into a punnet square, you would get a 25% chance of homozygous brown eyes, 50% chance of heterozygous brown eyes and a 25% chance of homozygous recessive blue eyes. Tim is that 25% that received a trait for blue eyes.