Match the following theories of ageing.
\[
\begin{array}{|l|l|}
\hline
\textbf{Theory} & \textbf{Description} \\
\hline
\text{P. Cellular-Clock Theory} & \text{(iii) Cells are limited in number of times they can reproduce to repair damage} \\
\hline
\text{Q. Wear-and-Tear Theory} & \text{(iv) Body organs and cell tissues wear out with repeated use and abuse} \\
\hline
\text{R. Free-radical Theory} & \text{(i) Oxygen molecule with unstable electron} \\
\hline
\text{S. Activity Theory} & \text{(ii) Elderly person who remains active in some way adjusts more positively to ageing} \\
\hline
\end{array}
\]