Sales book is a record of:

Only cash sales of goods
Only sale of assets
Only credit sales of goods
All sales

The correct answer is D. All sales.

A sales book is a book of original entry that records all sales made by a business. It is used to track the amount of sales made, the type of products or services sold, the date of the sale, and the customer who made the purchase. The sales book is also used to calculate the total sales revenue for a business.

Option A is incorrect because a sales book records all sales, not just cash sales. Option B is incorrect because a sales book records all sales, not just the sale of assets. Option C is incorrect because a sales book records all sales, not just credit sales of goods.