This is a problem on blood type. each parent has 3 alleles, {a, b, o}. each parent gives one allele to the offspring, and the combination (known as genotype) determines the blood type of the offspring, {a, b, ab, o}.

hello which   of the following there is nothing!

sorry, but you do not have posted the diagram.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.