Đáp án:

 B

Giải thích các bước giải:

Ta có:

\(\begin{array}{l}
{f_1} = \dfrac{{{\omega _1}}}{{2\pi }} = \dfrac{1}{{2\pi \sqrt {L{C_1}} }} = \dfrac{1}{{2\pi \sqrt {{{2.10}^{ - 3}}{{.70.10}^{ - 12}}} }}\\
 \Rightarrow {f_1} = 425359,48Hz\\
{\lambda _1} = \dfrac{c}{{{f_1}}} = \dfrac{{{{3.10}^8}}}{{425359,48}} = 705m\\
{f_2} = \dfrac{{{\omega _2}}}{{2\pi }} = \dfrac{1}{{2\pi \sqrt {L{C_2}} }} = \dfrac{1}{{2\pi \sqrt {{{2.10}^{ - 3}}{{.530.10}^{ - 12}}} }}\\
 \Rightarrow {f_2} = 154584,94Hz\\
{\lambda _2} = \dfrac{c}{{{f_2}}} = \dfrac{{{{3.10}^8}}}{{154584,94}} = 1940m
\end{array}\)

#Sadboy