Which of the following uses a 24-pin connector to supply power to the motherboard?

Correct answer: ATX power supply

Option C is correct because ATX power supplies use the 24-pin main power connector (evolved from the original 20-pin ATX12V standard) to supply the motherboard with multiple voltage rails including 3.3V, 5V, and 12V. Option A is incorrect because Molex connectors are 4-pin peripheral connectors historically used for IDE drives and fans, not for powering the motherboard directly. Option B is incorrect because PCIe power connectors are 6-pin or 8-pin connectors used to supply additional power to discrete graphics cards, not the motherboard main power. Option D is incorrect because SATA power connectors are 15-pin connectors used to power SATA storage devices such as hard drives and SSDs.