Consider the following data:

 

For which period was the natural growth rate maximum?

Growth rate = Birth rate – Death rate

Growth rate for 1911-1921 = 48.1 – 35.5 = 12.6

Growth rate for 1941-1951 = 39.9 – 27.4 = 12.5

Growth rate for 1961-1971 = 41.1 – 18.9 = 22.2

Growth rate for 1971-1981 = 37.1 – 14.8 = 22.3

We have to assume the simple formula for natural growth rate, as above, because nothing else is mentioned. And check only for the options given, not all seven years.