Correct Answer: (a) Humayun's Mausoleum
Solution:During his stay in Delhi in November 2010, the then president of USA Barak Obama went to see Humayuan's Mausoleum. Humayun's Tomb, Delhi built in 1570, is of particular cultural significance as it was the first garden-tomb on the Indian subcontinent. It inspired several major architectural innovations, culminating in the construction of the Taj Mahal.