What is the only contiguous barrier reef in north america?

Florida Keys

Explanation:

Its the reef system of the North America and is the main coral living reef and it covers about 221 miles and runs along the Florida southeast coast and it's protected by the underwater state parks in the john Penne kamp of the united states.

D. continental rift

343^x = 49^4-xx = 4-xx+x=42x = 4x = 4/2x = 2therefore x = 2