Why is the Sydney-to-Melbourne race regarded as one of the toughest marathon events in the world?
A.
Because the Sydney-to-Melbourne race is 875 kilometers long .
B.
Because the Sydney-to-Melbourne race is a harsh test of endurance for the world’s top athletes.
C.
Because the Sydney-to-Melbourne race is held in Sydney.
D.
Because the Sydney-to-Melbourne race is held by the United Nations.