Correct option is D
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Gallium arsenide phosphide (GaAsP) is a semiconductor material commonly used in the manufacture of
red, orange, and yellow LEDs. By varying the proportions of gallium, arsenic, and phosphorus, different wavelengths of light (colors) can be emitted.
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Gallium phosphide (b) is used for green LEDs.
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Gallium arsenide (c) is primarily used for infrared LEDs.
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Gallium (a) alone does not produce light-emitting properties.
