Question

a man with type a blood marries a woman with type b. their offspring all have type ab blood. the pattern of inheritance is called a codominance. b sex - linkage. c crossing over. d incomplete dominance.

Explanation:

Type A blood (homozygous AA) and type B blood (homozygous BB) produce AB offspring where both A and B antigens are fully expressed. This is codominance—both alleles are dominant and manifest simultaneously. Sex-linkage relates to X/Y chromosomes, crossing over is genetic recombination, and incomplete dominance shows a blended trait (neither fully expressed), so these are incorrect.

Answer:

A. codominance.