Which statement demonstrates enforcement of the monroe doctrine?
a. the united states convinced japan to open trade relations.
b. the united states allowed hawaiians to import sugar duty free.
c. the united states insisted that great britain submit a boundary dispute with venezuela to arbitration.
d. the united states competed against france and britain for asian markets.

norsemen from northern countries had made earlier journeys

depends on the age of the teen, many believe by the age of 16 a person should know the strong difference between right and wrong along with the difference between risky and immediate death. swimming with sharks might be dangerous but swimming with sharks while bloody meat is attached to you is just insane. even more if you have no idea what you're doing. however, no matter the age, as long as the person is skilled enough and has the mental and physical capacity to control their actions doing whatever sport they put their mind to is all that matters.