Assuming we have three linked genes for a specific plant. The allele for purple (P) flowers are dominant over the white (p) flowers, the allele for tall (T) plants is dominant over short (t) plants, and the allele for smooth (S) stems is dominant over the hairy (s). A testcross is performed by crossing a plant with PpTtSs genotype with the true-breeding plant with ppttss genotype. They yield the following progeny: 

Which of the following genes are more closely linked to each other?