Please choose the correct ending to complete the given sentence: Health: [header] How to activate thermacare heat wraps [title] Unwrap the heat wrap thirty minutes before use. [step] The chemical ingredients in thermacare wraps need to be exposed to air to activate. Once exposed to air, the wrap should immediately begin heating, reaching its maximum temperature in about half an hour.

Ending1: Attaching the wrap too early will limit its exposure to air, causing it to heat more slowly. [substeps] Do not microwave the wrap, or attempt to speed up the warming by heating it in any other fashion. Ending2: [substeps] There are a few precautions you must take regarding opening the wrap before using a thermacare on your entire body when it is hot outside. You must also take steps: stand close to a wall with plenty of space in between the heat wrap and the wall and ceiling. Ending3: Make sure that the wraps are not exposed to the heat coming from the candles/fans/jars, through the open oven door, or in the freezer. [title] Place one layer of foil on top of the wrapped wrap. Ending4: [substeps] Do not open the wrap until you have activated each ingredient without doing so. You may wish to break the wrap open to better see, or set a timer for a few minutes, so that you do not open the wrap while doing so.

Answer format: ending1/ending2/ending3/ending4