5. (1st Grade 11 "Hope Cup" Test 2) $f$ is a one-to-one mapping from $\mathbf{R} \rightarrow \mathbf{R}$, the function $y=f(x)$ is strictly increasing, the solution set of the inequality $x>f(x)$ is $P$, and the solution set of the inequality $x>f[f(x)]$ is $Q$, then
A. $P \varsubsetneqq Q$
B. $P=Q$
C. $Q \mp P$
D. $P \varsubsetneqq Q$ and $Q \varsubsetneqq P$