Statement b is correct: Exercise Yudh Abhyas is the largest running joint military training and defence cooperation endeavor between India and the USA. The exercise was started in 2004 under the US Army Pacific Partnership Program. The exercise is hosted alternately between both countries. The exercise aims at enhancing understanding, cooperation and interoperability between two Armies. 

Source: Indian Army Contingent Departs for 17th Edition of Indo-US Joint Military Exercise “Ex Yudh Abhyas 2021” at Joint Base Elmendorf – Richardson, Alaska(USA)