Why Were Canals an Improvement Over Roads for the Transport

Why were canals an improvement over roads for the transport of goods?

A) Road transportation was slow and expensive; goods could be transported faster and less expensively by canal.
B) While road construction was expensive, canals were much cheaper to build.
C) While roads were best suited to transporting bulky goods, canals were better for transporting luxury goods.
D) Since most American roads ran east to west, canals provided north-to-south links.