Four people $\mathrm{P}, \mathrm{Q}, \mathrm{R}$, and $\mathrm{S}$, of different ages, make the following observations.
$\mathrm{P}$ - I am younger than $\mathrm{S}$.
$\mathrm{Q}$ - I am neither the youngest nor the oldest.
$\mathrm{R}$ - $\mathrm{P}$ is older than me.
Based on these observations, the youngest person is $\_\_\_\_$.
- $\mathrm{P}$
- $\mathrm{Q}$
- $\mathrm{R}$
- $\mathrm{S}$
