Explanation

Types of gametes = 2 ௡ n=Number of heterozygotes considered, i.e., monohybrid cross(n =1), dihybrid cross (n =2), trihybrid cross (n =3) and so on. AA BB CC × aa bb cc is a trihybrid cross, therefore, different types of gametes are = 2 ௡ = (2) 3 = 2 × 2 × 2 = 8