To find the common ratio, you compare a few pairs of consecutive terms, by dividing an element by its predecessor.
12 / 72 = 1/6
2 / 12 = 1 / 6
1/3 / 2 = 1 / 6
The ratio is constant... so that's your common ratio to go from one term to the next.
To go from one term to the next, you have to multiply by 1/6.
C) you can withdraw your earnings once you are 59.5 years old without paying a penalty