His definition of public opinion, the author states that the opinions of private individuals become public opinion when they

I believe the answer is: are openly expressed

Private opinion could only exist in one person's mind,. While it might be provide the most safety and unlikely to cause conflict, it would never be able to change how people think or behave. the second that individual express their opinion to other people, it create a high chance of causing a conflict. But,the chance of other people hearing it and change their opinion  goes up along with it.

balearic sea - is a body of water in the mediterranean sea around the balearic islands. baltic sea - is a mediterranean sea of the atlantic which is enclosed by scandinavian and baltic countries. barents sea - is a marginal sea in the artic ocean located off the northern coast of norway and russia.

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.