Context: This passage describes the flower form trait in rose plants:

In a group of rose plants, some individuals have double flowers and others have single flowers. In this group, the gene for the flower form trait has two alleles. The allele F is for double flowers, and the allele f is for single flowers.
A certain rose plant from this group has single flowers. This plant has two alleles for single flowers.
Based on this information, what is this rose plant's phenotype for the flower form trait?
A. single flowers
B. ff
From the given choices, select the correct answer and reply with the letter of the chosen option.

A