Recently, linking of which of the following rivers was undertaken?

The answer is B, Godavari and Krishna. The 2015 Pattiseema lift irrigation project in Andhra Pradesh lifted Godavari water near Pattiseema and moved it through the Polavaram Right Main Canal into the Krishna basin, reaching the Krishna delta near Jaggayyapeta. This was the link that was actually undertaken in the period the question refers to.

The core concept is inter-basin water transfer, which is part of the National Water Development Agency's proposals under the National Perspective Plan. It matters for Mains GS-II and GS-III on federal water disputes and river interlinking.

• A (Cauvery and Tungabhadra): Only proposed, and the Cauvery dispute keeps it contested.
• C (Mahanadi and Sone): Listed under the Peninsular component of the National Perspective Plan, but not implemented.
• D (Narmada and Tapti): Also a proposal in the plan, with no completed link.

Since 2016 the picture has changed. The Ken-Betwa link, signed under the National River Linking Project in 2021, is the first inter-state link being taken up at scale, so a current-affairs answer may point to it instead. For this 2016 question, the Godavari-Krishna transfer is the correct choice.

Trap: Aspirants who recall the NRLP's 30 priority links may pick C or D, since those were in the plan. Check what was actually executed, not what was proposed.