Bihar has a relatively young population, with a significant proportion of people:

Above the age of 65
In the working-age group (15-64)
Below the age of 15
Evenly distributed across all age groups

The correct answer is: c) Below the age of 15.

Bihar has a relatively young population, with a significant proportion of people below the age of 15. According to the 2011 census, 39.3% of the population of Bihar was below the age of 15, compared to the national average of 26.5%. This means that there are more children and young people in Bihar than in most other states in India.

There are a number of reasons for this. One reason is that Bihar has a high fertility rate. The average woman in Bihar has 3.2 children, compared to the national average of 2.2 children. This means that there are more births in Bihar than in most other states.

Another reason for the young population of Bihar is that there is a high rate of migration from Bihar to other parts of India. Many young people from Bihar leave the state in search of better opportunities. This means that the population of Bihar is aging more slowly than the population of other states.

The young population of Bihar presents both challenges and opportunities. On the one hand, it means that there is a large pool of potential workers. On the other hand, it also means that there is a large number of people who need to be educated and employed. The government of Bihar is working to address these challenges by investing in education and job creation.

Option a) is incorrect because the proportion of people above the age of 65 in Bihar is relatively small. According to the 2011 census, only 6.8% of the population of Bihar was above the age of 65, compared to the national average of 8.6%.

Option b) is incorrect because the proportion of people in the working-age group (15-64) in Bihar is not significantly higher than the national average. According to the 2011 census, 53.9% of the population of Bihar was in the working-age group, compared to the national average of 55.9%.

Option d) is incorrect because the population of Bihar is not evenly distributed across all age groups. As discussed above, there is a large proportion of people below the age of 15 in Bihar.