A Maze Experiment Uses 24 Lab Rats of Various Ages

Multiple Choice

A maze experiment uses 24 lab rats of various ages, as summarized here:
$$\begin{array} { | l | l | } \hline \text { Age (in months) } & \text { Number of rats } \\\hline 2 & 4 \\\hline 3 & 6 \\\hline 4 & 6 \\\hline 5 & 4 \\\hline 7 & 3 \\\hline 9 & 1 \\\hline\end{array}$$ What is the median rat age (in months) for this maze experiment?

A) 3.5
B) 4
C) 4.5
D) 5