In Amsterdam (阿姆斯特丹) , there is an unusual Children Restaurant. It is run (经营) by children. From the manager to the cooks, waiters and other members are all children from six to twelve years old. They themselves do all the necessary work such as cooking and cleaning. These children are selected (挑选) in Amsterdam. After training (培训), they may work in the Restaurant for four weeks. All of them like their work. This restaurant was founded (创办) in 1983 by a woman cook, who wanted to give the children chances to learn to be useful to the public. And now she is the only adult (大人) there, but her job is just to take care of the children. The Restaurant is welcomed almost by everyone. Since there are only 20 seats in the Restaurant, it is always full of people. If you want to have a meal in the restaurant, you must tell them ahead of time (提前). The cost of a meal is different according to different people. Usually four dollars for each adult, but much cheaper for the children. And its business hours are only on Saturday evenings and Sunday afternoons. How many seats are there in the restaurant

A. 20.
B. 10.
C. 30.