Find the measure of Arc BO. B 0 63° S 52° E​

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.

Element 17 is chlorine it is a group 7 element(halogen) and belongs to period 3 of the periodic table