What types of barriers might prevent trade between countries in economics?

abraham lincoln  (february 12, 1809  – april 15, 1865) was an american statesman, politician, and lawyer who served as the 16th  president of the united states  from 1861 until  his assassination  in april 1865. lincoln led the nation through the  american civil war, its bloodiest war and its greatest moral, constitutional, and political crisis.[2][3]  he preserved the  union,  abolished slavery, strengthened the  federal government, and modernized  the u.s. economy.

c. archbishop desmond tutu promoted the acknowledgement of the rights of black africans and expose human rights abuses.

d. leader haile selassie modernized african society through the institution of progressive social, economic, and educational reforms.