Write the next sentence in the following story.

How to measure a mattress
Take off any sheets, blankets, or pillows on your mattress.
You'll get the most accurate measurements when your mattress doesn't have anything on it. If you're measuring your mattress for fitted sheets or a comforter, and you have a padded mattress topper on your mattress, leave it on when you do the measuring.

Possible answers:
(1). You'll know you're measuring the mattress if you see any attachment marks on the mattress. Don't take the width and length of your mattress in just one " measure ".;
(2). Don't see the label on your mattress listed below or in the instructions. Similarly, if the label tells you to measure a mattress for fitted sheets, don't buy it in a discount store.;
(3). Measure from the left side to the right side of your mattress to get the width. Use a tape measure or fabric ruler to do your measuring.;
(4). Be careful not to put down a blanket when measuring, because this increases your risk of forgetting the measurements. You can tuck a sheet into the topper.;. The answer should be
(3).