The correct answer is option 4, NekChand. The Rock Garden of Chandigarh was created by NekChand, an Indian artist. NekChand started building the garden secretly in 1957, using recycled materials and urban waste. The garden covers an area of about 40 acres and is made up of various sculptures and art pieces, all created by NekChand.

Option 1, Khushwant Singh,is incorrect. Khushwant Singh was an Indian author and journalist, but he was not the creator of the Rock Garden.

Option 2, Charles Corbusier, is incorrect. Charles Corbusier was a famous architect, but he did not create the Rock Garden.

Option 3, Edward Baker, is incorrect. There is no significant information or evidence to suggest that Edward Baker was involved in the creation of the Rock Garden.