hi !
A = I've (I have) = j'ai (avoir) is the correct answer (but j'ai isn't slang !!)
B= I'm = je suis (être)
C = We've = nous avons (avoir)
D = We're = nous sommes (être)
to have = avoir
J'ai
tu as
il/elle/on a
nous avons
vous avez
ils/elles ont
To be = être
je suis
tu es
il/elle/on est
nous sommes
vous êtes
ils/elles sont
very often , you may make mistakes as we do in English, because for example in English, you say "I'm sixteen " as we say "J'ai 16 ans" and we can't shorten the words as you with "I'm" or "can't".....
hope it helps to understand