Decimals....

we have 10 numbers with even tenth digit and 20 numbers with odd tenth digit
set 1 = x.2, x.4, x.6, x.8
set 2 = x.1, x.3, x.5, x.7, x.9

case I:
if all even tenth digit numbers are of type x.2 then the gain in summation of these nos is max (0.8 * 10) = 8
if all odd tenth digit number are of type x.9 then the loss in summation of these nos is max (0.9 * 20) = 18

so diff = 8 - 18 = -10

case II:
if all even tenth digit numbers are of type x.8 then the gain in summation of these nos is max (0.2 * 10) = 2
if all odd tenth digit number are of type x.9 then the loss in summation of these nos is max (0.9 * 20) = 18

so diff = 2 - 18 = -16

case III:
if all even tenth digit numbers are of type x.2 then the gain in summation of these nos is max (0.8 * 10) = 8
if all odd tenth digit number are of type x.1 then the loss in summation of these nos is max (0.1 * 20) = 2

so diff = 8 - 2 = 6
(*note: diff cannot be 10 as the maximum gain - minimum loss after rounding up/down is 8 - 2 = 6)

Answer choice which says 1 and 3.

What is OA?