In a monohybrid cross, there are 3 types of genotypes produced in the F₂ generation: AA, Aa, aa. In a dihybrid cross, there are $3\times 3=9$ types of genotypes produced in the F₂ generation: AABB, AaBB, aaBB, AABb, AaBb, aaBb, AAbb, Aabb, aabb. In a trihybrid cross, there are $3\times 3\times 3= 27$ types of genotypes produced in the F₂ generation (number of different F₂ genotypes is 3n) and they are: