Consumer's Income = $12 Refer to the Data

Consumer's income = $12 $$\begin{array}{l}\begin{array} { c c c c } \begin{array} { c } \\\text { Units of } \\\text { Product }\\\hline\end{array} & \begin{array} { c } \\\text { Marginal Utility, X } \\( \text { Price } = \$ 1 ) \\\hline\end{array} & \begin{array} { c } \\\text { Marginal Utility, Y } \\( \text { Price } = \$ 1 ) \\\hline\end{array} & \begin{array} { c } \text { Marginal Utility, }\\\text { New Product, Z } \\( \text { Price } = \$ 1 ) \\\hline\end{array} \\ \text { First } & 12 & 16 & 20 \\\text { Second } & 10 & 14 & 18 \\\text { Third } & 8 & 12 & 16 \\\text { Fourth } & 6 & 10 & 14 \\\text { Fifth } & 4 & 8 & 12 \\\text { Sixth } & 2 & 6 & 10 \\\text { Seventh } & 0 & 4 & 8\end{array}\end{array}$$ Refer to the data.Assume new product Z is introduced.How many units of Z will this consumer buy,given his or her $12 budget?

A) Zero units.
B) 2 units.
C) 4 units.
D) 6 units.