b
for maximum current, circuit must be in resonance

\(\mathrm{f}_0=\frac{1}{2 \pi \sqrt{\mathrm{L} \times \mathrm{C}}}\)

\(\mathrm{f}_0=\frac{1}{2 \pi \sqrt{100 \times 10^{-3} \times 2.5 \times 10^{-9}}}\)

\(=\frac{1}{2 \pi \sqrt{25 \times 10^{-11}}}\)

\(=\frac{1}{2 \pi \times 5} \times 10^5 \times \sqrt{10} \mathrm{~Hz}\)

\(=\frac{100}{10} \times 10^3 \mathrm{~Hz}\)

\(\mathrm{f}_0=10 \times 10^3 \mathrm{~Hz}\)