number properties

[sud21]

If a and b are none negative integer, ab=?
1). 4^a=2^b
2). 2^a=3^b

[neelgandham]

If a and b are none negative integer, ab=?

1). 4^a=2^b

2^2a = 2^b
Implies 2a = b,
If a = 0, b = 0, ab = 0
If a = 1, b = 2, ab = 2
If a = 2, b = 4, ab = 8.. Insufficient to answer ab=?

2). 2^a=3^b

a=0 and b=0 is the only solution set. Hence sufficient!

IMO B