It is important to maintain septic systems in order to
a. prevent treated sewage from contaminating groundwater
b. process human waste into fertilizer
c. prevent untreated sewage from contaminating groundwater
d. none of the above

answer; ok in rural area most people depend on private transportation(cars),pick up truck,donkey and buggy: ),and urban people can walk or ride public transportation,bus,train cab,uber.

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.