The answer is: d. Reiko should add other foods to the menu and offer discounts to attract more people to her restaurant.
According to Adam smith, Producers need to provide a product that is needed by the market in order to obtain profit, not the other way around.
Since the majority of the people in the cities did not like Japanese food, Seiko need to accept the fact that there is not enough demand for that particular food and start to develop new menus that attract the locals (she can do this by mixing some characteristics from Japanese food with western food).
On top of that, offering discounts create an incentives for the consumers to come and try the new products.