18.
The answer is: B
Explanation
The correct option is B: Incurable.
S.93 of the Indian Evidence Act treats the patent ambiguity as incurable. This means that when the language used in a document is, on its face, ambiguous or defective, evidence may not be given of facts which would show its meaning or supply its defects.
For example, if A agrees, in writing, to sell a horse to B for "Rs. 1,000 or Rs. 1,500", evidence cannot be given to show which price was to be given. The ambiguity in the document is patent, or apparent from the words themselves, and cannot be cured by extrinsic evidence. The rationale behind this rule is that the parties should express their intention clearly and unambiguously in the document, and that the court should not rewrite the contract for them by admitting evidence of facts that are not stated in the document.