Which of these rules was part of the caste system

a. a person could change his status through achievement, such as gaining wealth
b. a person was born with a social category could advance through good behavior
c. a person of higher social standing could not marry a person of lower social standing
d. a person could do the same work as his or her parents or do somthing differant.

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".

what was the significance of the plessy vs ferguson ruling and jim crow laws

answer the impact. plessy v. ferguson allowed 'separate but equal, also known as segregation, to become law in the united states