Answer:
Option D
Explanation:
Given
Justin has type A blood . Both the parents of Justin has AB blood type
Brittany has type B blood and both the parents of Brittany has AB blood type
This make it clear that -
Genotype of Justin is AA
Genotype of Brittany is BB
Now if Justin is crossed with Brittany , following blood groups in offspring is possible -
AA * BB
AB, AB, AB, AB
Thus, none of the offspring will have A blood group. Thus the chances that Justin and Brittany's son has type A blood is
%
Option D is correct
Crossing over occurs between prophase I and metaphase I and is the process where two homologous non-sister chromatids pair up with each other and exchange different segments of genetic material to form two recombinant chromosome sister chromatids. So the answer would be Prophase l. Hope this helps