As part of their effort to measure behavior carefully, many behaviorists restricted their research to studies using

answer: hey improve the marine life in a certain area.

they provide a new location for fishermen to fish and which works to ease the pressure on natural reefs.

they are a great way to get rid of large objects that would otherwise be placed on landfills

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.