Body parts supplied by vein or artery.
a.) Hepatic artery - liver
b.) Carotid artery - Brain, neck, and face.
c.) Thoracic aorta - Thorax
d.) Aorta - the Main artery supplies blood to down parts of the body from the heart.
e.) Cranial vena cava - Cranium
f.) Caudal vena cava - Tail.
If less is the only option then go with that like your question suggests but more feels like a better answer
The correct option is A.
The DNA from one specie differ from the DNA of another specie on the basis of their base ratio. The base ratio refers to the percentage of purine to pyrimidine in a DNA molecule. The base ratio is the one that is responsible for the variability that is observed in chromosomes from different species.
The X symbol looks too much like the multiplication symbol, it also makes using it as a variable more confusing.