Answer: B) The ratio should be 3:1
Explanation: The genotypes of the offsprings from a monohybrid cross between a male and female rat with genotype Bb will produce 2 Bb, 1 BB and 1 bb. Phenotypically, Bb and BB will manifest outwardly as dominant while Bb will appear as recessive trait. Therefore, the phenotypic ratio is 3:1
See the attached punnet for the cross