(c) At resonance, $\omega L = \frac{1}{\omega C}$
Current flowing through the circuit,
$I = \frac{V_{R}}{R}$
$= \frac{100}{1000} = 0.1\ A$
So, voltage across L is given by
$V_{L} = IX_{L} = I\omega L$
But $\omega L = \frac{1}{\omega C}$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ V_{L} = \frac{1}{\omega C}$
$= \frac{0.1}{200 \times 2 \times 10^{- 6}} = 250\ $V