Boxes of packets of sweets are delivered to a shop. There are 17 boxes.
Each box holds 42 packets.
How many packets of sweets are there?

Yes you are right the correct answer is b

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.