Please choose the correct ending to complete the given sentence: Education and Communications: [header] How to demonstrate the greenhouse effect [title] Place the thermometers in direct sunlight. [step] Put them on a concrete or wood surface that is in direct sunlight outside. Allow them to sit in the sun for 3 minutes.

Ending1: After this time, look for small, bug-like insects that hang out from the thermometers to help refresh the plants. [substeps] If you place the thermometers close to the heated center of the greenhouse, they will remain in direct sunlight. Ending2: [substeps] Set the timer or clock to 3 minutes so you know when the time is up. You can also place the thermometers under a sun lamp for 3 minutes if you are creating a model indoors. Ending3: After the sun sets, the thermometer will go into the lab for an additional 15 minutes. [substeps] Put some rocks, pebbles, vases or greenery around the thermometers. Ending4: [title] Use a squat lamp to check the thermometer. [step] An thermometer should read 25 degrees f (13 degrees c).

Answer format: ending1/ending2/ending3/ending4