A box contains 12 chocolates, 3 of which are white chocolate, 4 milk chocolate, and 5 dark chocolate. I am sharing the box with three of my friends. The four of us take turns, each one drawing a chocolate at random from those available in the box. Yes, we're drawing without replacement. We intend to eat the chocolates, not put them back.
Politely, I let my friends draw before me.
For each of the subparts, provide your answer as an unsimplified fractional expression.

a) What is the chance that I draw a dark chocolate?
b) Given that none of my friends draws a dark chocolate, what is the chance that I draw a dark chocolate?
c) What is the chance that all four of us draw milk chocolates?
d) What is the chance that the friend who gets to select first draws a dark chocolate and I draw a dark chocolate too?