The linking of rivers in India is a long-standing proposal aimed at improving the availability of water resources, irrigation, and hydroelectric power generation across the country. The project involves the interlinking of rivers by constructing a network of canals, reservoirs, and dams.

Out of the given options, the linking of Godavari and Krishna rivers has been undertaken by the Indian government. This project is known as the "Godavari-Krishna Linking Project" and is part of the larger "Interlinking of Rivers" (ILR) project.

The Godavari-Krishna Linking Project involves the construction of canals and reservoirs to transfer surplus water from the Godavari river to the Krishna river basin. The project aims to provide irrigation facilities to the drought-prone areas of Andhra Pradesh, Maharashtra, and Karnataka, and to generate hydroelectric power.

The project involves the construction of two main canals: the Polavaram Right Bank Canal (PRBC) and the Pattiseema Lift Irrigation Scheme (PLIS). The PRBC canal will divert water from the Godavari river to the Krishna river basin, while the PLIS scheme will pump water from the Godavari river to the Krishna river basin during the dry season.

It is important to note that the interlinking of rivers project has been a topic of controversy and debate. Critics argue that the project could lead to ecological damage, displacement of people, and the diversion of funds from other crucial development projects.

In conclusion, the linking of Godavari and Krishna rivers has been undertaken by the Indian government as part of the larger Interlinking of Rivers project. The project aims to provide irrigation facilities and hydroelectric power to the drought-prone areas of Andhra Pradesh, Maharashtra, and Karnataka. However, the project is not without its controversies, and its impact on the environment and local communities needs to be carefully considered.