🔍 Key Concepts

• Greenhouse gas "potency" is usually measured by global warming potential (GWP), not just by how much of it is emitted. • Compare typical exhaust components from LNG (liquefied natural gas) fueled engines versus conventional diesel: which gas is especially associated with natural gas systems? • Understand that some gases can be present in small quantities but still have a much higher warming effect per molecule than CO2.

💭 Think About

• Among the choices, which substance is most directly related to natural gas (LNG) composition itself? • Which of these gases is widely discussed in climate science as having a significantly higher global warming potential than CO2 over a 20-year or 100-year period? • Are any of these options primarily known for toxicity/odor rather than for being a major greenhouse gas in climate reports?

✅ Before You Answer

• Identify which listed gas is the main component of natural gas (LNG). • Recall which gas IPCC reports often describe as having a much higher GWP than CO2. • Eliminate options that are mainly known as toxic or smelly trace gases rather than key greenhouse gases in engine emission discussions.