What Made Portolan Charts So Much More Useful for Explorers

What made portolan charts so much more useful for explorers and sailors?

A) The new maps traced the primary routes that connected the various ports.
B) The new maps showed ocean currents and wind currents.
C) The new maps highlighted where the most expensive materials were located.
D) The new maps were completely waterproof.
E) The new maps pointed out where indigenous people were weakest and less able to defend themselves.