The pedigree below shows several generations of a family in which cystic fibrosis runs. A healthy phenotype is dominant (C), and cystic fibrosis is recessive (c). Shaded individuals have cystic fibrosis. Symbols with question marks have unknown genotypes and phenotypes. Individual 3 must have a genotype of:
A. CC
B. C
C. cc
D. None of the above
