Which of the following is correct

The correct answer is Option D: All the above.

In the context of the Indian Contract Act, these options pertain to specific scenarios where pledges are considered valid:

- Option A: A pledge made by a mercantile agent is valid. A mercantile agent is a person who, in the ordinary course of business, has authority to pledge goods as security. Such pledges are recognized as valid under certain conditions.

- Option B: A pledge made by a person in possession under a voidable contract is valid. A voidable contract is one that is initially valid but can be voided by one of the parties due to factors like fraud or misrepresentation. Until the contract is voided, any pledge made by a person in possession is considered valid.

- Option C: A pledge by a person having a limited interest is valid to the extent of that interest. This means that if someone pledges property in which they have a limited or partial ownership interest, the pledge is valid only to the extent of that ownership interest.

So, Option D: All the above is correct because all three scenarios mentioned in Options A, B, and C can result in valid pledges under specific circumstances as defined by the Indian Contract Act.