Answer:
He is either not carrying the gene for RP or the RP gene has mutated.
Explanation:
RP or Retina Pigmentosa is an eye defect inherited by a person from a parent. The disease is degenerative as the individual gradually loses his sight. It normally starts off as night-blindness and could go as bad as a total loss of sight.
The mutation of both the RPGR and RP2 genes which are responsible for the function and structure of light-reception in the eye accounts for most cases of Retina Pigmentosa disease.
One of the most important benefits that wetlands provide is their capacity to maintain and improve water quality. When healthy, wetlands have a rich natural diversity of plants and animals. These can act as filtering systems, removing sediment, nutrients and pollutants from water.
:D
C is the most likely answer to this question.