In Mendel’s crosses, the trait is visible in the F2 generation, but not the F1 generation.

In Mendel’s crosses, the recessive trait is visible in the F2 generation, but not the F1 generation.  

After crossing a tall pea plant with a short pea plant, all of Mendel’s pea plants were tall because it is the Dominant trait.  

For seed color, the F2 generation produced both yellow and green seeds because there are two different alleles for each gene.

If you'd like to know more, read on:

Alleles are variants of genes that control traits. There are two alleles called the dominant and recessive allele.

A dominant allele is a trait that is physically expressed even when coupled with a recessive allele. A recessive allele on the other hand is the trait that is masked by the dominant allele.

This is what happened in Mendel's crosses. He crossed a true-breeding tall plant with a true breeding short plant.

P generation

TT - Tall plant

tt - Short plant

The result in the F1 generation that consisted only of Tt plants, where the dominant allele was expressed.

   T    T

t   Tt   Tt

t   Tt   Tt

Then he crossed the F1 generation to produce the F2 generation.

Tt x Tt

The results:

    T    t

T  TT   Tt

t    Tt    tt

As you can see the resulting offsprings shows that the recessive trait occurring, tt. This means that there was a 25% chance that the off springs produced would short plants and 75% that the offsprings produced is tall. This applies also to the color of the seeds if we cross the pea plants based on the color of seeds.

Explanation:

the correct option is option d