How do I convince my parents to let me have a baby ragdoll kitten?

Hi,
I love animals more than anything. We have a dog but my friends cat had kittens and she is selling them for free! they are so flufffy and cute and nice. I always take very good care of animals and my parents know that, but how do I convince them to get a cat if there IS a way.
to the first few smart *** people: A)I am as responsible B)and I never said “selling” C) and NO they did not “refuse” they said they’d think about it AND I am asking for answers NOT questions.

thank you.