(3) In the Cartesian coordinate plane $x O y$, point $A(5,0)$. For some positive real number $k$, there exists a function $f(x)=a x^{2}, a>0$, such that $\angle Q O A=2 \angle P O A$, where $P(1, f(1))$ and $Q(k, f(k))$, then the range of $k$ is ( ).
(A) $(2,+\infty)$
(B) $(3,+\infty)$
(C) $[4,+\infty)$
(D) $[8,+\infty)$
(3) Since $02$. Therefore, the answer is A.



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