The Pedigree Shown Here Pertains to a Trait Due to a Rare

The pedigree shown here pertains to a trait due to a rare, X-linked recessive mutation. Individual 1 has an affected grandfather, but the genotypes and phenotypes of individuals 1-4 are unknown. What is the probability that individual 1 is heterozygous? What is the probability that individual 3 is heterozygous? What is the probability that individual 4 is affected?

A) 1; 1/4; 1/4
B) 1; 1/2; 1/2
C) 1/2; 1/4; 1/2
D) 1/2; 1/2; 1/2
E) 1/2; 1/4; 1/4