The flowchart below shows the three generations of a cross between a pea plant that has yellow pods and a pea plant that has green pods. Green pods are the dominant trait. The flowchart is missing the labels that describe the traits.

The question is incomplete. Complete question has been attached.

3. A,C and D

Explanation:

According to Mendel's law of inheritance, allele for green pods is dominant over allele for yellow pods.

In first generation when the parents were crossed, entire progeny in second generation showed only one trait. Considering that dominant trait is always expressed over recessive trait, second generation must have the dominant trait i.e. green pods. So, square C should have green pods.

First generation must have one green pod parent which resulted in green pods the entire second generation. The third generation has both green pods and yellow pods.  The only option in which three squares have green pods is option 3 (A, C and D) so it is the correct answer.