Gastrointestinal, Genitourinary, and Reproductive Systems From Paramedic Emergency Care 3rd Edition Progress Indicator: Question 3 of 20 3.  What is methane (CH4)? Choices: A colorless, odorless and tasteless combustible gas. A colorless, odorless and tasteless poisonous gas. A colorless, odorless and tasteless gas which supports combustion. A colorless, odorless and tasteless inert gas.