Three crops that contribute maximum to global food grain production are:

The three crops that contribute maximum to global food grain production are wheat, rice, and maize. These crops are the most widely grown and consumed crops in the world, and they are the primary source of food for many people. So, the correct answer is option A. Notice that the other options are not correct. Sorghum and barley are also important crops, but they are not as widely grown or consumed as wheat, rice, and maize.