Test 1 question 43:
About 5% of individuals in a particular population are known to carry a recessive gene for poliodystrophy, an inherited disorder characterized by recurrent seizures and dementia with onset in early childhood. A 32-year old healthy woman who had a brother with this disorder seeks genetic counselling. The patient's husband, an only child, does not know if his family has a history of the disorder. What is the probability that the patient is a carrier of poliodystrophy?
the answer is D. does anyone know how to approach the question?