Independent assortment
Explanation:
The type of inheritance displayed by the offspring is a simple independent assortment inheritance according to Mendelian law.
The result of crossing BbGg and bbgg is as follows (see the attached image)
4 BbGg smooth and gray
4 Bbgg smooth and white
4 bbGg bumpy and gray
4 bbgg bumpy and white
The phenotype ratio from the cross is 1:1:1:1 as far as the independent assortment is concerned.
Now, looking at the population of each phenotype from the cross
Smooth, gray 119
Smooth, white 123
Bumpy, gray 121
Bumpy, white 117
119:123:121:117 is approximately equal to 1:1:1:1.
Hence, the cross agrees with Mendel's law of independent assortment of genes.