Fact 1: Most people can survive only a few days without water.

Fact 2: Water combines hydrogen and oxygen.

Given the two facts above, answer the question "Most people can survive only a few days without a combination of what?" with the following options: 
- dehydration
 - hydrogen and oxygen
 - food and shelter
 - hydrogen chloride and water
 - scarce resources
 - solid, liquid, gas
 - lemonade and ice water
 - watercolor paints


 

  hydrogen and oxygen       