Which statement best contrasts I2C and SPI protocols?

Which statement best contrasts I2C and SPI protocols?

• A. I2C uses two wires (SDA, SCL) and supports addressing; SPI uses four wires (SCK, MOSI, MISO, SS) and typically has no inherent addressing.
• B. I2C is faster than SPI in typical use.
• C. SPI allows multiple masters with addressing.
• D. I2C uses four wires and no addressing; SPI uses two wires and addressing.

Answer: (A)

The key difference here is how the two protocols handle wiring and addressing. I2C uses only two wires, SDA and SCL, and is designed for multiple devices on the same bus. Each device has a unique address, so the master communicates with a specific device by addressing it on the bus. This built-in addressing lets many devices share the same two-wire bus. SPI uses four wires: a clock line, master-out-slave-in, master-in-slave-out, and a separate slave-select line for each device. While you can connect multiple devices, there’s no inherent addressing in the protocol itself—each device is selected by pulling its own SS line active. So addressing is achieved by hardware selection rather than a bus address. Therefore, the statement that I2C uses two wires and supports addressing while SPI uses four wires and typically has no inherent addressing best contrasts the two. The other options mix up which protocol is faster or how many wires and addressing are used.

The key difference here is how the two protocols handle wiring and addressing. I2C uses only two wires, SDA and SCL, and is designed for multiple devices on the same bus. Each device has a unique address, so the master communicates with a specific device by addressing it on the bus. This built-in addressing lets many devices share the same two-wire bus.

SPI uses four wires: a clock line, master-out-slave-in, master-in-slave-out, and a separate slave-select line for each device. While you can connect multiple devices, there’s no inherent addressing in the protocol itself—each device is selected by pulling its own SS line active. So addressing is achieved by hardware selection rather than a bus address.

Therefore, the statement that I2C uses two wires and supports addressing while SPI uses four wires and typically has no inherent addressing best contrasts the two. The other options mix up which protocol is faster or how many wires and addressing are used.