This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to relieve chronic back pain naturally
Choose the right mattress.
You may not realize it, but on average, people spend about a third of their lives lying in bed. Therefore, choosing the right mattress plays an important role in managing back pain.

Available options: (1). Therefore, you should pick a mattress that fits your needs and your lifestyle. The ideal mattress should be put in the right, relatively flat place. (2). Start by choosing a mattress that allows you to transport yourself comfortably. If you feel like you can do well without a mattress, then try sleeping on your back. (3). You know your body and back best. Though you should choose a mattress based on personal preference, try staying away from soft mattresses. (4). Standard mattresses can provide excellent support for an entire torso-including your back. If you are overweight, you may want to ramp up the load to avoid popping issues when you sleep.
The answer is:
(3).