Series circuit: same current, use I-V graphs for voltages

Steps:

• Identify current I from resistor's I-V graph at 3 V p.d.
• Use this I for the lamp, as series components share current.
• Read p.d. across lamp from its I-V graph at current I.
• Obtained value is 14 V.

Why D is correct:

• Kirchhoff's circuit laws require total p.d. sums, but here I-V graphs directly give lamp's voltage at shared current I, yielding 14 V per graph data.

Why the others are wrong:

• A: Misreads resistor graph, underestimating current and thus lamp voltage.
• B: Confuses resistance values, ignoring nonlinear lamp I-V curve.
• C: Assumes ohmic behavior for lamp, which is incorrect for filament.

Final answer: D