The correct answer is option 'C', which states that the letter of credit is not required for obtaining an export license. Let's understand why this is the case.

Explanation:
1. IEC Number: The IEC (Import Export Code) number is a unique identification number issued by the Directorate General of Foreign Trade (DGFT) to individuals or businesses involved in importing or exporting goods and services. It is a mandatory requirement for obtaining an export license as it identifies the exporter and allows them to engage in international trade.

2. Registration cum Membership Certificate (RCMC): RCMC is a certificate issued by a recognized Export Promotion Council or a commodity board in India. It acts as proof of registration with the council or board and is required for availing various benefits and privileges provided by the government to exporters. It is an essential document for obtaining an export license.

3. Letter of Credit: A letter of credit is a financial instrument issued by a bank on behalf of a buyer, guaranteeing payment to the exporter upon fulfillment of certain conditions. It is commonly used in international trade to ensure secure payment for goods and services. However, it is not a document required for obtaining an export license. Instead, it is a part of the payment process between the buyer and the seller.

4. Bank Account Number: A bank account number is the unique identifier assigned to an individual or business account held at a bank. While having a bank account is necessary for conducting financial transactions related to exports, it is not specifically required for obtaining an export license. However, having a bank account is beneficial as it facilitates smooth payment transactions and record-keeping.

In conclusion, the letter of credit is not required for obtaining an export license. The IEC number and RCMC are essential documents that establish the identity and registration of the exporter, while a bank account number is necessary for financial transactions.