I just read the Pigeon Hole Principle and have a few questions of which I could make out neither head nor tail :(

1. 17 ants are roaming over a chessboard of area 8x8 (64 sq. inches) then atleast 2 of them mustr be always closer than :

(a) 2 inches (b)$2\sqrt{2}$ inches (c) $\sqrt{2}$ (d) none

2. Out of (m+1) given integers 2 of them can be chosen such that their :

(a) difference is divisible by m (b) sum is div. by m

(c) product is div. by m (d) none

3. Justify giving arguments that there are 2 people in Chandigarh having same date of birth

(donno if Chandigarh has any importance)