Which ACTN3 genotype (RR, RX, or XX) would provide these Olympic marathon athletes with an advantage, and why?

XX

Explanation:

ACTN3 genotype i.e. XX provides advantage to the Olympic marathon athletes because it strengthens the fiber of the muscles. This gene is also called the gene of speed. This ACTN3 gene has a great influence on the type of fiber that makes body muscles, and they are also linked to strength and endurance so we can conclude that this gene provides benefits to the Olympic marathon athletes by giving strength to the fiber of muscles.

XX

Explanation:i am nerd ;-;

i believe it would be c: tons.