During the 1828 campaign andrew jackson became the first candidate to a. promise better times if he was elected b. appeal directly to other politicians for support c. praise his opponents accomplishments d. appeal directly to the voters for support

i think it would be a

explanation:

the addition to geographic boundaries that might have  kept the people of the huang river civilization from traveling to far distance region is that they had learned about the other river valley civilizations but feared contact would bring invasion.

hope this .

plz give me brainliest!