Write the next sentence in the following story.

How to patch a leak in an air mattress
Know that all air mattresses lose air naturally.
Before you decide to strip the covers off of you mattress and search for holes, know that no air mattress holds air indefinitely. You will naturally have to re-inflate your mattress whether or not you have a leak.

Options: a. With proper air mattresses, you can be able to slide out of your mattress and return to your mattress with ease. If the leak is deep, the mattress may not handle air as much. b. Air mattresses leak by partially releasing pressure, causing your mattress to collapse and the air inside of your mattress to enter the small, unsightly holes. To get rid of a leak, you need to reshape your mattress. c. Cold air, for example, causes your mattress to shrink. As the house cools down at night, your air mattress will likely soften a bit as the air cools. d. Inspect the mattress over a night to find any damage. Once the mattress has been stripped of its air, inspect it carefully for any obstruction.. The answer should be
c.