Ron has recovered from a bullet wound that he suffered as an innocent bystander during a violent bank robbery. But he has begun to experience trouble sleeping, is easily startled, and feels increasingly detached from his family and friends. Ron is most clearly showing symptoms of

c. taught scientists many new things about the earth, but not other planets.

explanation:

the correct answer is modern american cars are not available due to trade restrictions.

trade between cuba and the united states have serious restrictions. the u.s. imposed an economic embargo on cuba, that among other things means that modern american cars are not available due to trade restrictions.

in response to some governmental actions of the authorities from cuba, president john f. kennedy proclaimed an embargo on trade between both countries in february 1962. the trade embargo remains active until this day and was implemented directly by the departments of commerce and the department of treasury.

in president trump’s administration, there is a national security presidential memorandum that "strengthens the policy of the u. s.", affecting trade with cuba.