A testcross on a tall pea plant produces only tall offspring. What is the genotype of the tall pea plant? A. Tt or tt

B. Tt

C. tt

D. TT

Option D, TT

Explanation:

As per the given situation, the cross on tall plant will give only tall offspring.

Let us take the cases one by one

a) Tt or tt

Here genotype "tt" does not represent a tall pea plant and hence, this option is incorrect

b) Tt

This genotype will produce heterogyzous tall pea plant but when the cross will be done between two pea plants having genotype "Tt", 50% of the offsprings will have "tt" genotype, thus they will not be tall. Hence this option is incorrect

c) tt

This genotype represent short pea plant, hence this option is incorrect

d) TT

This genotype represent homozygous tall pea plant and when a cross is carried out between two homozygous tall pea plants, all the offspring plant will be tall with genotype "TT". Hence, this option is correct.