For $4.00 per month, Van can send or receive 200 text messages. Each additional message costs $0.05. If Van can spend at most $9.00 per month on
text messages, find the greatest number he can send or receive each month

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.