The Table Contains Data for a Hypothetical Single-Product Economy

Multiple Choice

$$\begin{array} { | c | c | c | c | } \hline \text { Year } & \text { Units of Output } & \text { Price of Bagel per Unit } & \text { Price Index (Year 1=100) } \\\hline 1 & 10 & \$ 10 & 100 \\\hline 2 & 12 & 20 & 200 \\\hline 3 & 15 & 30 & 300 \\\hline 4 & 20 & 40 & 400 \\\hline\end{array}$$ The table contains data for a hypothetical single-product economy. Real GDP in year 3 is

A) $100.
B) $450.
C) $225.
D) $150.