The population of the world is estimated to be 7×109 . The population of the United States is estimated to be 3×108. Choose the phrase that completes the sentence. The world population is the population of the United states.

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.