Series currents are equal in identical components

Steps:

• Identify circuit configuration: three identical lamps likely in a mix of series and parallel, with ammeters measuring branch currents.
• Note lamp equivalence: identical resistances mean equal current sharing in parallel paths.
• Analyze ammeter positions: I1 and I2 measure current through the same series path or equivalent branches.
• Compare readings: currents in series segments or symmetric parallels are identical, so I1 equals I2.

Why D is correct:

• Kirchhoff's current law ensures equal currents in series-connected identical lamps, as total current divides equally in parallels but remains same in series paths.

Why the others are wrong:

• A: I2 ≠ I3 if I3 measures a different branch, like total current.
• B: I1 ≠ I2 if they are in unequal branches; I3 not necessarily smaller.
• C: No basis for I1 > I3 > I2 without unequal resistances or voltages.

Final answer: D