The correct answer is: c) Mustard
Mustard is a cover crop that is grown to improve soil health and fertility. It is a nitrogen-fixing crop, which means that it can take nitrogen from the air and convert it into a form that plants can use. This helps to improve the fertility of the soil and can also help to reduce erosion. Mustard is also a good source of organic matter, which helps to improve the structure of the soil and can also help to improve water retention.
Maize, wheat, and pulses are all cereal crops. Cereal crops are not grown as cover crops because they do not have the same benefits as mustard. Cereal crops do not fix nitrogen, so they do not improve the fertility of the soil. They also do not add organic matter to the soil.
In conclusion, mustard is the best crop to grow as a cover crop to improve soil health and fertility. It is a nitrogen-fixing crop that adds organic matter to the soil. Maize, wheat, and pulses are not good cover crops because they do not have the same benefits as mustard.