Bradford Would Like to Write a Query That Returns the Average

Multiple Choice

Bradford would like to write a query that returns the average unit sales over the last 30 days for each of his bakery's product types: cupcakes, muffins, and cookies. There are several flavors of each in the table, but the product types are identified in a CATEGORY column as "Cupcake," "Muffin," or "Cookie." What should the last part of his query be, following the part shown below? ​
SELECT CATEGORY, AVG(UNIT_SALES) FROM PRODUCTS

A) ORDER BY CATEGORY;
B) GROUP BY CATEGORY;
C) BETWEEN ('Cupcake', 'Muffin', 'Cookie') ;
D) WHERE CATEGORY IN ('Cupcake', 'Muffin', 'Cookie') ;