The correct answer is option 'B' which includes the Southern tributaries of river Ganga in Bihar as Son, Punpun, Kiul, and Chandan.

Explanation:
The Ganga, also known as the Ganges, is one of the major rivers in India that flows through several states, including Bihar. It is considered a sacred river by Hindus and holds great religious and cultural significance.

Southern tributaries of river Ganga in Bihar:
1. Son River:
- The Son River is the largest southern tributary of the Ganga in Bihar.
- It originates in the Amarkantak hills of Madhya Pradesh and flows through the states of Jharkhand and Bihar before joining the Ganga near Patna.
- The Son River is approximately 784 kilometers long and drains a large portion of central and eastern Bihar.

2. Punpun River:
- The Punpun River is another important tributary of the Ganga in Bihar.
- It originates near the Jharkhand-Bihar border and flows through the districts of Gaya and Patna before merging with the Ganga near Fatuha.
- The Punpun River is approximately 135 kilometers long and is known for its fertile plains.

3. Kiul River:
- The Kiul River is a small tributary of the Ganga that flows through Bihar.
- It originates in the Jamui district and joins the Ganga near Barh.
- The Kiul River is approximately 180 kilometers long and plays an important role in irrigation and agriculture in the region.

4. Chandan River:
- The Chandan River is a tributary of the Kiul River and ultimately the Ganga.
- It originates in the Nawada district and flows through the districts of Nalanda and Patna.
- The Chandan River merges with the Kiul River near Barhiya.

These southern tributaries of the Ganga in Bihar play a crucial role in the socio-economic development of the region. They provide water for irrigation, support agriculture, and contribute to the overall ecology of the area. The rivers also hold cultural and religious significance for the people of Bihar, and their waters are considered sacred.