C. Sales Book

The correct option is C) Sales Book.

The sales book is a special book of original entry used to record credit sales made by a business. It is also known as the Sales Day Book or Sales Journal. In this book, all credit sales transactions are recorded in chronological order as and when they occur.

Explanation:
When goods are sold on a credit basis, it means that the buyer does not make an immediate payment but instead promises to pay at a later date. In this case, the goods were sold on a credit basis to A Brothers for Rs. 1,000.

The sales book is the appropriate book to record this transaction because it specifically deals with credit sales. The purpose of the sales book is to provide a record of all credit sales made by the business, allowing for easy tracking and monitoring of these transactions.

The sales book typically includes the following information for each credit sale:
- Date of the transaction
- Invoice or sales number
- Name of the customer
- Description of the goods sold
- Quantity of goods sold
- Selling price per unit
- Total amount of the sale

By recording the credit sale in the sales book, the business can keep track of its accounts receivable and also have a clear record of all credit sales made during a given period. This information is then used for various purposes, such as issuing invoices to customers, calculating sales commissions, and preparing financial statements.

In summary, the sales book is used to record credit sales transactions, and since the goods were sold on a credit basis to A Brothers, the correct option is C) Sales Book.