What Do Inactive Armies Do ?

What does Inactive Armies Do ?

Anyone knows the answer to A) & B) Questions 1) ?

A) Allied Armies

1) If you attack an enemy pop ctr, will it help out ? ________

2) If you attack an enemy army(ies), will it help out ? Answer :- YES

B) Enemy Armies

1) If allied pop ctr where it is, is attacked by enemy army(ies), will it help out
? ________

2) If attacked by an enemy army(ies), will it defend ? Answer :- YES

b.e.