Based on this information, what is this plant's phenotype for the fruit sheen trait?

 - glossy fruit
 - dull fruit
The cucumber plant's genotype for the fruit sheen gene is ff. The cucumber plant's genotype of ff has only f alleles. The f allele is for glossy fruit. So, the cucumber plant's phenotype for the fruit sheen trait must be glossy fruit.
To check this answer, consider whether the cucumber plant's alleles are dominant or recessive. The allele for dull fruit (F) is dominant over the allele for glossy fruit (f). This means F is a dominant allele, and f is a recessive allele.
The cucumber plant's genotype of ff has only recessive alleles. An organism with only recessive alleles for a gene will have the recessive allele's version of the trait. So, the cucumber plant's phenotype for the fruit sheen trait must be glossy fruit.