Question 40·Easy·Command of Evidence
A student is giving a short talk about how scientists use Antarctic ice cores to estimate past atmospheric carbon dioxide (CO2) levels. The student includes the graph shown. During the talk, the student notes that from 1700 to 1850 ____
Which choice most effectively uses the data to complete the student's observation?
For a command-of-evidence question with a graph, limit your attention to the exact time range named in the sentence. Read the relevant data points directly from the axes, then pick the choice that matches both the direction (increase/decrease) and the approximate size of the change.
Hints
Use only part of the graph
Look at the section of the graph from 1700 through 1850, not the later years.
Compare endpoints
Read the approximate CO2 values at 1700 and 1850, then compare them.
Check size of the change
Decide whether the change is small or large, and whether the values stay below a certain level.
Step-by-step Explanation
Locate the relevant years
Focus only on the data points at 1700 and 1850 on the graph.
Read the CO2 values
The CO2 value is about 276 ppm in 1700 and about 281 ppm in 1850.
Describe the change using the graph
The increase is only about ppm, and both values are under 285 ppm, so the best completion is: "the estimated CO2 concentration rose by only about 5 ppm and remained under 285 ppm for the entire period."