If a pea plant producing yellow seeds (Yy) is crossed with a plant producing green seeds (yy), what ratio of plants producing yellow and green seeds would you expect in $F_1$ generation?

The correct option is A 1 : 1
In pea plants, yellow colour of seeds is dominant over green colour of seeds.

Let's suppose that the allele responsible for yellow colour of seeds is Y and the allele responsible for green colour of seeds is y.

When a plant heterozygous for yellow seeds (Yy) is crossed with a plant producing green seeds (yy), then the ratio of plants producing yellow seeds and green seeds in $F_1$ generation is 1 : 1

$F_1$ genotypic ratio: Yy : yy = 1 : 1
$F_1$ phenotypic ratio: Yellow seeds : Green seeds = 1 : 1