If GCD(a,b)=5\text{GCD}(a, b) = 5GCD(a,b)=5 and LCM(a,b)=100\text{LCM}(a, b) = 100LCM(a,b)=100, what could be the pair (a,b)(a, b)(a,b)?
(5,100)(5, 100)(5,100)
(10,50)(10, 50)(10,50)
(20,25)(20, 25)(20,25)
(5,20)(5, 20)(5,20)