What Feature Contributed to Galveston's Boom in the Last Three

What feature contributed to Galveston's boom in the last three decades of the 19^th century?

A) a coral reef off the coast that protected the city from flood waves
B) a deep-water port that was fit for steam-powered ocean liners
C) a mountain range that shielded the city from the region's hostile climate
D) an enormous oil deposit under the city that assured the town's prosperity