Correct Answer: Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

Solution : The correct answer is (a) Both the assertion and reason are true, and the reason is the correct explanation of the assertion.

The assertion is true. The agricultural reforms implemented during the period of 1951-1991 in India did aim to modernize Indian agriculture and increase agricultural productivity. These reforms were undertaken to address the challenges faced by the agricultural sector, improve productivity, and promote rural development.

The reason provided is also true. The reforms included the adoption of new farming techniques, such as the use of high-yielding crop varieties and improved agricultural practices. Additionally, the reforms aimed at improving irrigation facilities to ensure better water availability for agricultural purposes. The increased use of fertilizers and other inputs was also part of the efforts to enhance agricultural productivity.

The reason correctly explains the assertion. The adoption of new farming techniques, improved irrigation facilities, and increased use of fertilizers were instrumental in modernizing Indian agriculture and increasing agricultural productivity during the reform period.

Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.