Correct Answer: (a) 13.14%
Note: According to census 1991, the total population of Bihar (including Jharkhand) was 8.637 crore. Out of this, rural population was 7.502 crore and urban population was 1.135 crore. Thus, 13.14 percent of the total population dwelled in cities. Since 13 percent is not given in the options, option (d) will be the closest answer. According to the final data of Census 2011, Bihar has 88.7 percent rural and 11.3 percent urban population.