Among the given options, the correct answer is option 4, Vitthal Bhai Patel. The President of the Central Legislative Assembly in August 1925 was Vitthal Bhai Patel. It is important to note that the Central Legislative Assembly was a legislative body in British India, which functioned from 1921 to 1947.

Option 1, C.R. Das, was not the President of the Central Legislative Assembly in August 1925.

Option 2, Motilal Nehru, was also not the President of the Central Legislative Assembly in August 1925.

Option 3, M.R. Jayakar, was not the President of the Central Legislative Assembly in August 1925.

Therefore, the correct answer is option 4, Vitthal Bhai Patel.