If an assumption leads to a contradiction, the assumption is and its negation is

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

It is b as the correct answer is 0.088, you are able to work these out on a calculator or without a calculator if you type in the exact sum that is given for harder questions like these!