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.
A is the right answer because it is.
The surface of a leaf has many tiny pores, called stomata. The stomata allow carbon dioxide into the leaf so that photosynthesis can occur. They also allow water to leave the leaf by transpiration. Plants that grow in full sunlight usually have most of their stomata on the shaded undersides of their leaves.