Which of the following does not belong to the group?

Posters, free samples, and window displays are all methods used to promote goods and encourage customers to buy them: posters and window displays catch the eye and draw attention to a product, while free samples let customers try a product before committing to buy it. All three are active, outward-facing ways of increasing sales.

Hoarding of goods means deliberately withholding stock from the market, often to create artificial scarcity or to wait for prices to rise. Rather than encouraging sales, it restricts supply and can even work against customers, so it does not belong with the sales promotion techniques.

This is why the group is: posters, free samples, and window display, all of which promote a product, and hoarding of goods, which is an unrelated and even undesirable business practice concerned with withholding stock.

When an exam asks which item does not belong to a group, check whether every other item shares one clear purpose; here, three items promote sales while the remaining one restricts supply.