All India Bar Examination (AIBE) 6-VI Previous Year Question Papers with Answers

The correct option is B: Valid. 

A past consideration under Indian law is valid, as per section 2(d) of the Indian Contract Act, 1872. This section defines consideration as an act or abstinence or promise done or made by the promisee or any other person at the desire of the promisor, and it states that the consideration may be past, present or future. This means that a promise can be based on something that the promisee or any other person has already done for the promisor before the promise was made, as long as it was done at the request of the promisor.

For example, if A finds B's lost wallet and returns it to him, and B promises to pay A Rs. 500 for his service, this is a valid contract based on past consideration. However, if A returns B's wallet without being asked by B, and B later promises to pay A Rs. 500, this is not a valid contract based on past consideration, as there was no request from B at the time of A's act 

The rationale behind recognizing past consideration in Indian law is to uphold the principle of justice and equity, and to prevent unjust enrichment of the promisor at the expense of the promisee.