The correct answer is option 'B' - 4 states.

Explanation:

River Krishna is one of the major rivers in India, which originates from the Western Ghats near Mahabaleshwar in Maharashtra and flows through several states before emptying into the Bay of Bengal.

The river Krishna flows through the following four states of India:

1. Maharashtra: The origin of the river Krishna is from the Mahabaleshwar hills in Maharashtra. Here, it is known as the Krishnaveni.

2. Karnataka: After flowing through Maharashtra, the river enters Karnataka and is joined by several tributaries such as the Ghataprabha, Malaprabha, and Tungabhadra. In Karnataka, the river is known as Krishnaveni, Kistna or Kaveri.

3. Telangana: The river Krishna then flows through Telangana, where it forms a natural boundary between Telangana and Andhra Pradesh. In Telangana, the river is known as Krishna.

4. Andhra Pradesh: Finally, the river Krishna enters Andhra Pradesh and flows through the districts of Krishna, Guntur, and West Godavari before emptying into the Bay of Bengal. In Andhra Pradesh, the river is known as Krishna.

Therefore, the correct answer is option 'B' - 4 states.