Task: Question Answering
Input (English): Problem: the annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years b in which the population would be doubled assuming there is no emigration or immigration is 
Options: a ) 20 , b ) 25 , c ) b = 30 , d ) b = 35 , e ) b = 40
Output (English): d