The correct answer is (a) Sir Pethick Lawrence.
The Cabinet Mission was a British mission to India in 1946 to negotiate a settlement between the Indian National Congress and the Muslim League over the future of India. The mission was led by Sir Pethick Lawrence, the Secretary of State for India.
The other options are incorrect.
(b) Lord Linlithgow was the Viceroy of India from 1936 to 1943.
(c) Lord Wavell was the Viceroy of India from 1943 to 1947.
(d) Sir John Simon was the head of the Simon Commission, which was sent to India in 1927 to investigate the possibility of granting India self-government.