In a pedigree, the individuals across many generations who carry the trait in question have their shapes shaded. The illustration has three generations. The first pair in the second generation had 4 offspring. It has shown that even with unaffected parents, the offspring could be afflicted with the disease. This suggests that the trait is recessive.
In the following human pedigree, how would you predict the trais to be passed on?
A. autosomal dominant
B. autosomal recessive
C. X-linked recessive
D. X-linked dominant
E. not enough information to predict