In order to assess your understanding of the lesson materials, please select the most appropriate answer for each of the multiple choice questions below.
    Question 1/6

    Where does natural gas come from?

    1. A
      Giant, underground caves filled with gas.
    2. B
      Porous rock, with gas in the holes
    3. C
      Subsurface aquifers
    4. D
      Tubing and casing