How does carbon intensity differ from energy intensity?

• A. Carbon intensity is energy consumed per unit of GDP.
• B. Energy intensity is CO2 emissions per unit energy.
• C. Carbon intensity is CO2 emitted per unit energy or per unit economic output.
• D. Energy intensity is CO2 emitted per unit of GDP.

Answer: (C)

The main idea here is to separate how much energy an economy uses from how much carbon it emits for that energy. Energy intensity measures how much energy is needed to produce a unit of economic output—essentially, it’s energy use per GDP and reflects energy efficiency and the structure of the economy. Carbon intensity, on the other hand, looks at how much CO2 is released for each unit of energy consumed, or for each unit of economic output; it combines the carbon content of the energy mix with the level of energy use.

The statement that carbon intensity is CO2 emitted per unit energy or per unit economic output captures this idea precisely—it's about emissions per energy or per GDP, tying together energy use and its carbon impact. In contrast, energy intensity is about energy per economic output, not emissions, so it doesn’t describe carbon content. The other options mix up these definitions, describing energy intensity or carbon intensity in ways that don’t fit the standard usage.