I need some help with the following problem:

You have 30 socks in a drawer, 10 red, 16 black and 4 blue. You are

removing socks from the drawer in the dark, so you cannot see the colours. How many socks do you need to take out to be certain you have:

(a) A matching pair of socks.

(b) Two matching pairs of socks.

(c) Two matching pairs of different colours.

(d) Two blue socks.

My attempt:

(a) The socks come in three possible colours. If we take one color of eeach sock, then take one more we will have at leasr 1 pair of 1 color: 3+1=4

(b) We must repeat process in (a) twice: 4+4=8

(c) If the first 16 we take all happen to be black and the next may 10 happen to be red so we have two matching pairs: 26 socks needed

(d) I think once all the blacks and reds are gone, we only need to take 2 more which will inevitibly be blue: 10+16+2=28.

I have a test so I appreciate it if anyone could please correct me.