Queens pawn openings

Why do all Openings with 1.d4 like Kings indian or Queens gambit have mainline 2.c4??
What should I do if my opponent chooses to play something else??

c4 is a quite normal choice for which u can decline by Nf6 or e6.if u opponent plays something else like e3 its also a normal line where u can push up e6 and later c5 which makes the center strong..there no much threats in the opening line of queen pawn.so u can just play with some careful attitude

c4 is a quite normal choice for which u can decline by Nf6 or e6.if u opponent plays something else like e3 its also a normal line where u can push up e6 and later c5 which makes the center strong..there no much threats in the opening line of queen pawn.so u can just play with some careful attitude

i i didn't read much after "u can decline by.."
I m not jus talking about Queens gambit.
I mean all queens pawn games ike nimzo indian,queens indian,kings indian
All of them start with 1.d4,e6 2.c4Nf6
Im asking the reason behind c4 but thanks for telling me the mainline for moves like 2.e3

pletchery....this thread or this website for that matter isn't the best place to advertise your coats.
Please stop spamming