If a plant has one dominant and one recessive form for height, why will it appear tall?

Correct answer: The dominant form masks the recessive form externally

The governing concept is a heterozygous genotype and phenotypic dominance. A plant with one dominant allele and one recessive allele has both forms in its genetic makeup, but the dominant allele controls the observable height under the usual Mendelian model. The recessive allele remains present but is not expressed in the phenotype. Therefore option A is correct; it does not mean the recessive allele has been destroyed.