Explanation:

- Option 1: Dube Commission

The Dube Commission is not related to the investigation of backward classes. It might refer to some other commission but not relevant here.

- Option 2: B.P. Mandal

B.P. Mandal headed the Mandal Commission, established in 1979 by the Janata Party government, to identify socially or educationally backward classes.

- Option 3: Kaka Kalelkar

The First Backward Classes Commission was set up in 1953 under the chairmanship of Kaka Kalelkar. It aimed to assess the conditions of socially and educationally backward classes.

- Option 4: U.N. Dheber

U.N. Dheber is not associated with any major commission regarding backward classes.