Aplant with a dominant homozygous trait is crossed with a plant with a recessive homozygous version of that trait. what is the probability that the offspring will display the dominant trait in its phenotype?

100%

Explanation:

If a plant is homozygous dominant, that means it carries 2 copies of the dominant allele (AA). A homozygous recessive plant carries 2 copies of the recessive allele (aa).

The attached punnet square shows this cross.

All of the offspring inherit an A from parent 1 and an a from parent 2. That means they are all heterozygous Aa. Therefore, they will all display the dominant trait phenotype.