Question

a population of red squirrelfish breeds and produce offspring, 75% are still red but 25% are yellow. this variation in the color of the squirrelfish can be explained by
a the presence of a mutagen in the environment that caused a color change.
b the rapid disappearance of the allele for red color in the fish population.
c the presence of a recessive allele for yellow color that was masked by a dominant red color allele
d (partially visible) the presence of an inhibitor protein that...

Explanation:

The 75% red and 25% yellow offspring ratio matches Mendelian genetics for a recessive trait. If red is dominant (R) and yellow is recessive (r), breeding heterozygous red parents (Rr × Rr) produces offspring with genotypes RR (25%), Rr (50%), and rr (25%). RR and Rr show red (75%), while rr shows yellow (25%). This means the yellow trait is from a recessive allele masked by the dominant red allele in parents. Mutagens cause random changes (not fixed ratios), red allele disappearance would reduce red offspring, and codominance would show mixed colors (not 75-25 split).

Answer:

C. the presence of a recessive allele for yellow color that was masked by a dominant red color allele