In a dihybrid cross between AABB and aabb the ratio of AABB, AABb, aaBb, aabb in F2 generation is

• A. 9 : 3 : 3: 1
• B. 1: 1: 1: 1
• C. 1: 2: 2: 1
• D. 1 : 1 : 2 : 2
• E. cessive