Explanation:

- Option 1: February, 1947 – Mr. Attlee did not announce the transfer of power in February 1947.

- Option 2: June, 1949 – By June 1949, India had already been independent for almost two years.

- Option 3: August, 1947 – Independence actually happened in August 1947, but the official announcement came before that.

- Option 4: June, 1948 – Mr. Attlee actually announced, in February 1947, that the British government would transfer power to Indian hands by June 1948.

The correct answer is: Option 4: June, 1948.