Solution:Defense Minister of India in chronological order:• Krishna Menon: He was an Indian academic, independence activist, politician, lawyer, and statesman.
During his time, Menon contributed to the Indian independence movement, India’s foreign relations as de facto foreign minister, one of the major architects of Indian foreign policy, and acted as Jawaharlal Nehru’s diplomat.
Menon became a member of the Rajya Sabha in 1953 from Madras. In 1956, he joined the Union Cabinet as Minister without Portfolio and was made Minister of Defence in April 1957, after winning the North Mumbai seat to the Lok Sabha.
• Jagjivan Ram: Popularly as Babuji, was an Indian independence activist and politician from Bihar.
In 1946, he became the youngest minister in Jawaharlal Nehru’s interim government, the first cabinet of India as a Labour Minister and also a member of the Constituent Assembly of India, where he ensured that social justice was enshrined in the Constitution.
Most importantly, he was the Defence Minister of India during the Indo-Pak War of 1971, which resulted in the creation of Bangladesh.
• Mulayam Singh Yadav: He was an Indian politician, a socialist figure and founder of the Samajwadi Party.
Over the course of his political career spanning more than six decades, he served for three terms as the Chief Minister of Uttar Pradesh, and also as the Union Minister of Defence in the Government of India.
In 1996, Yadav was elected to the eleventh Lok Sabha from Mainpuri constituency. In the United Front coalition government formed that year, his party joined and he was named India’s Defence Minister in the Devegowda ministry.
• Major Jaswant Singh: He was an officer of the Indian Army and an Indian Cabinet Minister.
He was one of the founding members of the Bharatiya Janata Party (BJP), and was one of India’s longest serving parliamentarians, having been a member of the Lok Sabha or the Rajya Sabha almost continuously between 1980 and 2014.
Singh was appointed as the Minister of Defence of India in the year 2000 after minister before him, George Fernandes was convicted in the Tehelka case and was forced to resign from his position.
• Manohar Parrikar: He was an Indian politician and leader of the Bharatiya Janata Party who served as Chief Minister of Goa from 14 March 2017 until his death.
Previously, he was Chief Minister of Goa from 2000 to 2005 and from 2012 to 2014 and from 2017 to 2019. He also served as the Minister of Defence from October 2014 to March 2017.
Therefore, the correct chronological order is (b), (a), (d), (c), (a).