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 foreign trade policy during 1951-1991 in India aimed to reduce the trade deficit. The trade deficit occurs when a country's imports exceed its exports, resulting in a negative balance of trade. The policy sought to address this imbalance by focusing on increasing exports and decreasing imports.

The reason is also true and provides the correct explanation for the assertion. By emphasizing the promotion of exports and reducing imports, the policy aimed to improve the trade balance and reduce the trade deficit. By generating more export earnings and limiting excessive imports, the goal was to strengthen the country's foreign exchange reserves and support overall economic growth.

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