Hillary Is 8 Years Old and Has Neuronal Ceroid Lipofuscinosis,also

Multiple Choice

Hillary is 8 years old and has neuronal ceroid lipofuscinosis,also known as Batten disease.It is autosomal recessive.She was fine until age five,when she began to lose her vision and stumble.She had learning difficulties in school and was diagnosed at age six.Hillary may only live into her twenties,experiencing dementia and seizures.Her younger brother Jaden,age six,is healthy,as are her parents.The probability that Jaden is a heterozygote is

A) 1/8.
B) 1/4.
C) 1/3.
D) 2/3.
E) 0.