Concept:In a parallel circuit, each bulb gets the full source voltage, so they glow with maximum brightness. In other arrangements, voltage is shared, reducing brightness.
Explanation:For identical bulbs, brightness depends on the voltage across each bulb.
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Arrangement A (all in series): Voltage is divided equally. Each bulb gets only one-third of the source voltage. So all bulbs glow dimly.
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Arrangement B (all in parallel): Each bulb gets the full source voltage. Therefore, all bulbs glow at their brightest.
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Arrangement C (two parallel in series with one): The two parallel bulbs get the same voltage (less than full source), and the series bulb gets even less. Brightness is not uniform and overall lower than Arrangement B.
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Arrangement D (two series in parallel with one): The two series bulbs share half the source voltage each, while the parallel bulb gets the full voltage. Brightness is uneven; the parallel bulb is brighter but the series pair are dimmer.
Thus, only Arrangement B gives maximum and equal brightness to all bulbs.
Answer:A. Arrangement B - All bulbs in parallel