Explanation:

- Let's look at the options:

- Bihar: This state has a high poverty *percentage*, but it's not the most populous.

- Madhya Pradesh: Also has a significant poverty population, but less than some bigger states.

- Maharashtra: While it’s very populous, its poverty rate is lower than other states.

- Uttar Pradesh: This is India's most populous state. It also has the maximum number of people living below the poverty line, simply due to the sheer size of its population.

- The correct answer is:

Option 4: Uttar Pradesh