Which is the correct verb form for this sentence?

living in a cold climate has been an easy adjustment for me, but it become more difficult dealing with the snow.

a.
have

b.
having

c.
has

ok so like i went to wiki and looked up the (constitution x new "hammystan")and it showed me the picture it highlights new hampshire and says first and second session and than it says that they hit up the u.s and was like "ey dude that paper u sent us was adopted it bro thx" xd syays it all on wiki/the pic

i dont really like reading so i guess other people might not like reading either so   imma put the answer in bold italics