1. The question asks for the location of the thermal power plant of Bokaro.
2. The Bokaro Thermal Power Station is located in Bokaro district.
3. Bokaro district was part of Bihar until November 2000, when the state of Jharkhand was created.
4. Since the question refers to the location generally (and was asked in 2003, after the creation of Jharkhand), the plant is located in the state of Jharkhand.
5. Therefore, the correct answer is (C) Jharkhand.