A5. Katarina baked three types of pastries and brewed tea and coffee, and she also has juice in the fridge. What is the maximum number of people Katarina can serve differently, if each person gets one piece of pastry and a drink?
(A) 6
(B) 9
(C) 15
(D) 18
(E) None of the above.
A5. Katarina has 3 types of drinks. To each, she can add a piece of pastry, which she chooses from three different types. Therefore, she has $3 \times 3=9$ different options.