To select a stir-fry dish, a restaurant customer must select a type of rice, protein, and sauce. There are two types of rices, three proteins, and seven sauces. How many different kinds of stir-fry dishes are available?
O $2+3 \cdot 7$
O $2+3+7$
O $2^3 \cdot 7$
O $2 \cdot 3 \cdot 7$