The correct option is A William Pitt the Younger
The Irish Rebellion of 1798 brought the Irish question forcibly to the attention of the British Cabinet; and William Pitt the Younger, the British prime minister, decided that the best solution was a union. The Act of Union came into effect on January 1, 1801, joining Ireland to Great Britain, creating the United Kingdom of Great Britain and Ireland. Hence, Option A is correct. Sir William Petty FRS (26 May 1623 – 16 December 1687) was an English economist, physician, scientist and philosopher. He first became prominent serving Oliver Cromwell and the Commonwealth in Ireland. Henry Addington was a British statesman who served as Prime Minister from 17 March 1801 to 10 May 1804. Spencer Perceval KC was a British statesman who served as Prime Minister of the United Kingdom from October 1809 until his assassination in May 1812. Since none of them were Prime Ministers in January 1801, these are incorrect options.