Answer: The phenotype of the genotype (rr) is wrinkled seeds.
Explanation: Dominant allele or gene is one which has the ability to express itself outwardly when it occurs together with a recessive allele. Dominant alleles are usually denoted in upper case for example R, T, A. Recessive allele or gene is one which lacks the ability to express itself in the presence of a dominant gene or allele. It is usually denoted in lower case, for example r, t, a.
Since R is for round seeds and r is for wrinkled seed; R is dominant while r is recessive, r will be able to express itself outwardly only when it occurs in a homozygous state such as in (rr). Therefore rr will manifest outwardly in the plant as wrinkled seed.