A Company Makes Four Kinds of Products Find Which of the Three Codes Is a Primary Key

Short Answer

A company makes four kinds of products. Each product has a size code, a weight code, and a shape code.
The following table shows these codes: $$\begin{array} { c c c c } & \text { Size Code } & \text { Weight Code } & \text { Shape Code } \\\# 1 & 42 & 27 & 42 \\\# 2 & 27 & 38 & 13 \\\# 3 & 13 & 12 & 27 \\\# 4 & 42 & 38 & 38\end{array}$$ Find which of the three codes is a primary key. If none of the three codes is a primary key, explain why.