This is a science question about genotypes/allele, that I could not figure out.?

Suppose you are growing purebred green-skinned watermelons. One day you find a mutant striped watermelon with purebred green watermelon. You cross the striped watermelon with a purebred green watermelon. Fifty percent of the offspring are striped, while fifty percent are solid green. Is the allele for the striped trait dominant or recessive? Explain your answer.