The correct answer is (b), Eastern area.
The eastern part of Uttar Pradesh is the most flood-affected area in the state. This is because the eastern part of the state is located in the Ganges basin, which is a major river basin in India. The Ganges River is prone to flooding, and when it floods, it can cause widespread damage to the eastern part of Uttar Pradesh.
The western part of Uttar Pradesh is also prone to flooding, but not as much as the eastern part of the state. This is because the western part of the state is located in the Yamuna basin, which is a smaller river basin than the Ganges basin. The Yamuna River is also prone to flooding, but it does not cause as much damage as the Ganges River.
The middle part of Uttar Pradesh is not as prone to flooding as the eastern and western parts of the state. This is because the middle part of the state is located in the Vindhya Range, which is a mountain range that protects the middle part of the state from flooding.
The northern part of Uttar Pradesh is also not as prone to flooding as the eastern and western parts of the state. This is because the northern part of the state is located in the Himalayas, which are a mountain range that protects the northern part of the state from flooding.