In a common emitter circuit if VCC is changed by 0.2 V, collector current changes by $4 × 10^{–3} mA$. The output resistance will be:

10 kΩ 30 kΩ 50 kΩ 70 kΩ

50 kΩ

$R=\frac{Δ_{knee}}{ΔI_{ce}}=\frac{0.2}{0.004×10^{-3}}=50 kΩ$