Explanation
An agreement is not voidable if consent is caused by:
A: Mistake as to an Indian law.
Explanation:
Out of the options listed, mistake as to an Indian law is the only circumstance where an agreement is not voidable due to the mistake. In the case of a mistake as to an Indian law, it may not render the agreement voidable because parties are generally expected to be aware of the laws of their own country. Mistakes about other aspects like misrepresentation, coercion, fraud, and undue influence can potentially make an agreement voidable, as they involve elements of deceit, pressure, or unfair influence. However, a mistake regarding the law, specifically Indian law in this context, does not have the same impact on the voidability of an agreement.