Solution: Wheat varieties like Sonalika and Kalyan Sona are semi-dwarf varieties developed by Norman E. Borlaug in Mexico in 1963.  These are drug-resistant varieties with a high yield. There are other two varieties as well, such as Himgiri which is resistant to stripe rust, leaf and hill blunt disorder, and other diseases, and Atlas 66 which is a high-protein biofortified hybrid wheat. So, the correct answer is (a).