Point out the wrong statement-

• A. If a contract consists of several letters, all the letters in which it is contained must be proved.
• B. If a contract is contained in a bill of exchange, that bill of exchange must be proved
• C. If the bill of exchange is written in three layers then only one is required to be proved.
• D. If 'A' gives receipt to 'B' of money paid by him and oral evidence of payment is produced, this evidence is not admissible.