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

How to use an inversion table for back pain
Secure your inversion table on a flat surface.
Ensure that all the joints, straps and pivot points are correctly connected. Do this every time you use the table in order to avoid a serious accident.

Select from the following.
(1). Stacking your work surface will make it easier to quickly locate and properly align your free elbow joints. Put a piece of paper on a flat surface.;
(2). Your table should not have a flap or other covering covering your inversion table. Any flap, especially if it is rolled up or screwed up, will prevent dust from entering it.;
(3). Assess if your patients are suffering from back issues. If the sufferer of back pain frequently has a problem in their back, try to fix the issue right away.;
(4). Read your inversion table instructional manual thoroughly before attempting to use the table. It will support your body weight, so it is important that all the steps are done correctly.;
The answer is:
(4).