When merging file certain required assumptions or conditions are required. What are some of these conditions?

a$)$ Make sure that matching variables have identical variable names.

b$)$ Make sure that cases are in the same order if you are adding new variables.

c$)$ Make sure that the variables are in the same order if you are adding new cases.

d$)$ Variables must be sorted first

e$)A$&$B$

f$)A,B$&$C$

g$)A,B,C$&$D$