Scenario CO₂ Is Not the Only Greenhouse Gas (GHG)that Impacts Global

Scenario
CO₂ is not the only greenhouse gas (GHG) that impacts global climate change. Other GHGs may be equally or more effective than CO₂ at trapping heat on Earth. Climate scientists determine how much a GHG may impact global warming based on two factors: the efficiency with which a GHG absorbs energy (i.e., traps heat on Earth) and the length of time (in years) that the gas remains in the atmosphere. A unit of measurement called the Global Warming Potential (GWP) is used to describe how much energy a GHG absorbs over a specific period of time (100 years is a standard time frame) . All GWP values of GHGs are compared to the GWP of CO₂, which is given a value of 1.
-In this scenario, how would you best describe CO₂?

A) It is a baseline comparison for the GWP values of all other GHGs.
B) It is a greenhouse gas whose GWP value is dependent upon the GWP values of all other GHGs.
C) It is the greenhouse gas that is the most efficient at trapping heat on Earth.
D) It is the greenhouse gas that is the least efficient at trapping heat on Earth.