With reference to Visible Light Communication (VLC) technology, which of the following statements are correct? 1) VLC uses electromagnetic spectrum wavelengths 375 to 780 nm. 2) VLC is known as long-range optical wireless communication. 3) VLC can transmit large amounts of data faster than Bluetooth. 4) VLC has no electromagnetic interference. Select the correct answer using the code given below:

The correct answer is C. Statements 1, 3 and 4 are right, and statement 2 is wrong. VLC carries data by modulating the intensity of light at very high speed, and a photodetector receives it. The visible band spans roughly 375 to 780 nm, so statement 1 holds. Visible light is not a radio signal, so VLC does not cause or suffer electromagnetic interference with RF equipment; statement 4 is correct.

• Statement 2 is wrong: VLC is short-range optical wireless communication. Light is blocked by walls and objects, so its useful range is limited to a room or small area. Long-range optical links, such as free-space optical links between buildings, are a different category.
• Statement 3 is right: VLC has shown gigabit-per-second data rates in laboratory and pilot setups, while classic Bluetooth runs at a few megabits per second. Bluetooth's strength is coverage and device ubiquity, not speed.

Core concept: optical wireless communication using the visible spectrum as the carrier, the basis of Li-Fi. For Mains GS-III (emerging communication technologies and digital infrastructure), the trade-off is high bandwidth and EMI immunity against line-of-sight and short range.

Trap: seeing "wireless" and "optical" and assuming long range like Wi-Fi or microwave links. The short-range limitation is what rejects statement 2.