Assertion (A): The Congress rejected the Cripps proposals. Reason (R): The Cripps Mission consisted solely of whites.

The correct option is B because while both statements are individually true, the reason provided does not explain the assertion.

Assertion A is true because the Indian National Congress rejected the Cripps proposals of 1942. The rejection was based on the mission's failure to promise immediate transfer of power and its inclusion of a provision allowing provinces to opt out of the Indian Union, which threatened the country's unity.

Reason R is also true because the Cripps Mission was headed by Sir Stafford Cripps and consisted entirely of British members.

However, the reason is not the correct explanation for the assertion. The Congress did not reject the proposals because the mission was composed of whites. In fact, many Congress leaders had a good personal rapport with Stafford Cripps. The rejection was based on the substance of the constitutional proposals, not the racial composition of the mission. This distinguishes it from the Simon Commission of 1927, which was primarily boycotted because it lacked Indian representation.