What is sentence four referring to (“But when a long train of abuses…for their future security.”)?

i do believe its (d) it allowed the government to offer pioneers sixty acres of western land if they lived on it and made improvements to it.

explanation: signed into law in may 1862, the homestead act opened up settlement in the western united states, allowing any american, including freed slaves, to put in a claim for up to 160 free acres of federal land. by the end of the civil war, 15,000 homestead claims had been established, and more followed in the postwar years

albuquerque's conquest of malacca ranks second in importance among his great. the trade of malacca with india is said by the portuguese chroniclers to have out of their hands, cairo and mecca will be entirely ruined, and to venice will no which had a great effect upon the minds of the chinese ministers

the map that was shown mostly had eastern asia highlighted. the answer would mostly likely be "the spread of communism into eastern asia set the stage for the korean war."

hopefully this .