The correct answer is (a) Rajasthan.
Rajasthan was the first state to issue Soil Health Cards to farmers in 2015. The cards provide information on the nutrient content of the soil, which helps farmers to improve their crop yields. The cards are also used to track the progress of soil health improvement over time.
Punjab, Haryana, and Maharashtra are also among the states that have issued Soil Health Cards to farmers. However, Rajasthan was the first state to do so.
Soil Health Cards are a valuable tool for farmers, as they can help to improve crop yields and reduce the use of fertilizers. The cards are also a good way to track the progress of soil health improvement over time.