The correct answer is option 2, "Lake". `Loktak` refers to the Loktak Lake, which is located in the state of Manipur, India. It is the largest freshwater lake in Northeast India and serves as an important ecological and cultural landmark in the region. The lake is known for its unique floating phumdis (massive vegetation islands) and is home to various flora and fauna, including the endangered Manipur brow-antlered deer and the sangai, Manipur`s state animal. The lake also has socio-economic significance as it supports fishing, agriculture, and tourism activities. So, `Loktak` is not a valley, river, or mountain range; it is a lake.