What's the single most important thing you need to survive in the wild?

• food
  The human body needs a minimum of 2 quarts (1.9 liters) of water per day for good health. One day without water is cause for serious concern, and three days without water will lead to almost certain death.
• water
  The human body needs a minimum of 2 quarts (1.9 liters) of water per day for good health. One day without water is cause for serious concern, and three days without water will lead to almost certain death.
• warmth
  The human body needs a minimum of 2 quarts (1.9 liters) of water per day for good health. One day without water is cause for serious concern, and three days without water will lead to almost certain death.