In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:
a. The allels of two genes are interacting with each other
b. It is a multigenic inheritance
c. It is a case of multiple allelism
d. The allels of two genes are segregating independently.
NCERT Class XII
Biology - Main Course Book
Chapter 5. Principle of Inheritance and Variation