What percentage of methane in air equals the Lower Explosive Limit (LEL)?

The Lower Explosive Limit (LEL) refers to the minimum concentration of a gas or vapor in air that can ignite and sustain a flame when an ignition source is present. For methane, the LEL is typically around 5% by volume in air. This means that any concentration of methane in air below 5% will not ignite, while concentrations above this level can potentially lead to explosive or flammable conditions depending on the concentration and presence of an ignition source.

Given that you're looking for the percentage that equals the LEL, 100% is not an accurate reflection of this limit as that concentration would be not only flammable but would also displace all oxygen required for combustion. The true value for methane's LEL being around 5% indicates that the correct understanding of explosive limits is crucial in fire safety and prevention strategies. Therefore, a reasonable way to interpret the question is that the actual LEL percentage is much lower than what is provided in the choices, and none of them accurately reflects the correct figure.