Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to feed a horse [title] Provide your horse with plenty of fresh, clean water. [step] Horses require between 5-15 gallons of water per day. If possible, make sure that your horse has access to water at all times.

Ending1: You can purchase containers to water your horse at the store, or make a makeshift water trough for feeding your horse in the barn. [substeps] Horses need about 100 gallons (24 square meter) of water per day, which is roughly one gallon of water for every 500 square feet of pasture. Ending2: If you do, feed your horse from a trough and a bowl of water whenever possible. [substeps] When a horse needs a water source at all times, place a trough or bucket on a clean stable floor or other surface for to splash water onto. Ending3: Horses do best drinking over the summer, when temperatures drop below 40 ° f (21 ° c). A healthy adult horse will drink at least two gallons of water each day. Ending4: Otherwise, make sure that you water your horse at least twice per day and allow several minutes for your horse to drink. [substeps] Make sure that the water in your horse's trough is clean and not frozen.

Answer format: ending1/ending2/ending3/ending4