The correct answer is (b) President of India.
The President of India is the only person who can commute a death sentence to any other punishment. This is because the President is the head of state and has the power to pardon or commute any sentence.
The Law Minister is a member of the Union Cabinet and is responsible for the administration of justice. However, the Law Minister does not have the power to commute a death sentence.
The Governor of a State is the head of the State and has the power to pardon or commute any sentence, except a death sentence. This is because the death sentence is a federal crime and only the President of India can pardon or commute it.
The Appropriate Government is the government of the State in which the crime was committed. The Appropriate Government has the power to grant remission of sentence, which means that it can reduce the length of a sentence. However, the Appropriate Government does not have the power to commute a death sentence.