About a deck of cards

Question

Answer the following about a standard deck of 52 cards:

A: How many cards must be drawn to be sure to have a pair?

B: How many cards must be drawn to be sure to have two spades?

C: How many cards must be drawn to be sure to have 2 cards of the same color?

The part that I am having trouble with is the "to be sure to have" requirement.

Answer 1

Guide:

This is not a probability type of question but pigeon hole principle. For example in part $C$, if we just draw $2$, we could have drawn red and black. What about $3$?