Since parent of both Justin and his wife Brittany have blood group ab, this means Justin is homozygous(aa) for blood group a and similarly his his wife Brittany is also homozygous (bb) for blood group b. Therefore, Justin and Brittany's son Theodore will certainly have ab blood group.
It helps the cell by making sure everything gets circulated throughout the cell
I believe the correct answer is A. Increases the rate of a chemical reaction. This is because they act as catalysts.
Among these options, the one which is the broadest group used to classify organisms is D. class.
Although it is not the broadest group ever phylum and kingdom are above it), it is the broadest one here.