I would say solve each diameter equation and order them fromleast to greatest, for example
1 Venus- 7.52×10 to the power of 3
So first simplify 10 to the power of 3 which is, 1000. Then you multiply 7.52 by 1000 which gets you 7520.
So solve each equation and order it
C is the answer cause 9 is the common factor
To the hundredth is 2 numbers after the decimal so since the third number is a 1 and its less than 5 it does no damage to the 9 therefore you just take away the one and you have your rounded answer, 12.79