Final answer:
Barack Obama was the President of the United States; the other individuals mentioned, Manmohan Singh and Haseena Sheikh, held different positions in other countries' governments.
Step-by-step explanation:
The president of the United States mentioned in the question is Barack Obama. During his presidency, Obama focused on significant challenges such as managing the economic recovery after the Great Recession, advancing the war on terror, and the implementation of healthcare reform. Barack Obama's presidency was marked by his multicultural background, which resonated with many Americans, and his story of challenges and perseverance that led him to the White House. Notable moments of his presidency include the successful raid on Osama bin Laden's compound in 2011.
It is important to note that Manmohan Singh was India's 13th prime minister and not the president of the USA. The other individuals mentioned, Haseena Sheikh (presumably referring to Sheikh Hasina, the Prime Minister of Bangladesh) and Arjan Singh (Marshal of the Indian Air Force), are also not related to the presidency of the United States.