While researching a topic, a student has taken the following notes:
<ul> <li>Studies of Antarctic ice cores reveal CO2 levels over the past 800,000 years.</li> <li>Pre-industrial CO2 typically ranged between 180 and 280 ppm.</li> <li>Current CO2 levels exceed 420 ppm (as of 2023).</li> <li>The current rate of increase is roughly 100 times faster than past natural transitions.</li> <li>Past CO2 changes occurred over tens of thousands of years.</li> </ul> The student wants to introduce a counterintuitive finding about the rate of recent CO2 change. Which choice most effectively uses relevant information from the notes to accomplish this goal?Which choice most effectively makes the student's point?
- A
Pre-industrial CO2 ranged between 180 and 280 ppm.
- B
Antarctic ice cores reveal CO2 levels over the past 800,000 years.
- Ccheck_circle
Although natural CO2 transitions historically unfolded over tens of thousands of years, the current rise is occurring roughly 100 times faster.
- D
Current CO2 levels exceed 420 ppm.
Explanation
A counterintuitive finding about the rate must contrast historical pace with current pace. Choice C does so explicitly. A is method, B and D give only one timeframe.