The pia mater is the deepest or innermost layer or meninges closest to brain that surrounds the brain and spinal cord both. It is a very thing transparent connective tissue. In this connective tissue there are vessels present for nutrient and blood supply.
Inflammation in the layer surround the brain is a condition known as Meningitis. This disease is normally caused by infection of the fluid surrounding the brain.
Thus, the correct answer is : connective tissue : pia mater
The type of mutation which is observed here is substitution mutation. According to the fact that sickle cell anaemia is occuring at the at beta-globin gene, the correct answer is c.substitution mutation as it shows mutation point as <span>a single base. Hope it will help! Regards.</span>