The correct answer is option 'A', Shri Lal Bahadur Shastri.
Let's understand the context and background of Bharat Ratna before discussing the first posthumous recipient.

Background of Bharat Ratna
- Bharat Ratna is the highest civilian award of the Republic of India, established in 1954.
- It is awarded in recognition of exceptional service or performance of the highest order in any field of human endeavor.
- The award may be given posthumously and does not carry any monetary grant.
- The recommendations for Bharat Ratna are made by the Prime Minister to the President, and a maximum of three recipients can be awarded in a year.

Shri Lal Bahadur Shastri
- Shri Lal Bahadur Shastri was an Indian politician and statesman who served as the second Prime Minister of India from 1964 to 1966.
- He played a significant role in India's struggle for independence and was associated with leaders like Mahatma Gandhi and Jawaharlal Nehru.
- Shastri is best known for his slogan "Jai Jawan Jai Kisan" (Hail the Soldier, Hail the Farmer) during the Indo-Pak war in 1965 and his emphasis on self-sufficiency in food production.
- He was known for his simplicity, integrity, and dedication towards the welfare of the nation.

Posthumous Award
- Shri Lal Bahadur Shastri was awarded the Bharat Ratna posthumously in 1966, after his sudden demise on January 11, 1966, in Tashkent, Uzbekistan.
- He passed away a day after signing the historic Tashkent Declaration, which aimed to resolve the Indo-Pak conflict.
- The decision to confer the Bharat Ratna on Shastri was made in recognition of his outstanding contributions to the nation as a leader and statesman.

Significance
- Shastri's posthumous award of Bharat Ratna holds great significance as it marked the recognition of his exceptional services to the nation, even after his untimely demise.
- It also symbolizes the respect and admiration that the nation had for his leadership and his commitment to the welfare of the people.
- Shastri's legacy continues to inspire generations, and his contributions to the nation are remembered with reverence.

In conclusion, the first posthumous recipient of Bharat Ratna was Shri Lal Bahadur Shastri. His exceptional leadership, dedication, and service to the nation were recognized by conferring this prestigious award on him, even after his untimely demise.