Read the following passage, then choose the correct answer to questions.
Today, supermarkets are found in almost every large city in the world. But the first supermarket (26)_________ opened only fifty years ago. It was opened in New York by a man named Michael Cullen.
A supermarket is different (27)___________other types of stores in several ways. In supermarkets, goods are placed on open shelves. The (28)__________ choose what they want and take them to the checkout counter. This means that fewer shop assistants are needed than in other stores. The way products are displayed is another difference between supermarkets and many other types of stores; (29)___________ example, in supermarkets, there is usually a display of small inexpensive items just in front of the checkout counter: candies, chocolates, magazines, cheap foods and so on.
Most customers (30)___________ go to a supermarket buy goods from a shopping list. They know exactly what they need to buy. They do the shopping according to a plan.
Điền vào số 30
A. who
B. what
C. which
D. whom
