A history teacher displayed average life expectancy at birth in the United States in four decades: 1900, 47 years; 1930, 60 years; 1960, 70 years; 1990, 75 years. The teacher concluded that life expectancy gains slowed substantially after mid-century. To support this, the teacher pointed to ______
Which choice most logically completes the text using the data above?
- A
the 1900 figure of 47 years.
- B
the average gain over the entire period.
- Ccheck_circle
the 13-year gain from 1900 to 1930 versus only a 5-year gain from 1960 to 1990.
- D
the 1990 figure of 75 years.
Explanation
"Slowed substantially" requires comparing gains across periods. Choice B contrasts a 13-year gain in the early period with only 5 years in the later period, directly supporting the slowdown claim.