Maximum height of a plant is 30ft and the minimum height is 10ft. If plant height is controlled by 3 pairs of genes then the height of a plant with genotype AaBbCc will be:

The correct option is D

19.9ft

The correct option is D.

Explanation of the correct option:

1. The number of polygenes is equal to 6.
2. The contribution of each polygene $=$ Maximum height of a plant $-$ Minimum height of a plant $/$ The number of polygenes $=(30-10)/6ft=3.3ft$
3. The contribution of the dominant polygene in the genotype AaBbCc $=(3.3\times 3ft=9.9ft$).
4. Therefore, the height of the plant with genotype AaBbCc $=$ Minimum height of the plant $+$ Contribution of the dominant polygene $=(10+9.9)ft=19.9ft$

Final answer: Maximum height of a plant is 30ft and the minimum height is 10ft. If plant height is controlled by 3 pairs of genes then the height of a plant with genotype AaBbCc will be 19.9ft.