Consider the following statements regarding the various proposals made during the Indian Freedom Struggle:

I. The August Offer (1940) was the first time the British explicitly promised the framing of a new Constitution by Indians themselves.

II. The Cripps Mission (1942) offered immediate transfer of constitutional powers but was rejected by Gandhi as a "post-dated cheque on a crashing bank."

III. The Wavell Plan (1945) proposed a "Three-Tier" grouping of provinces into Sections A, B, and C to satisfy the Muslim League.

IV. The Mountbatten Plan (1947) mandated a plebiscite in the North-West Frontier Province (NWFP) and the Sylhet district of Assam.

Which of the above statements are correct?