The correct answer is 1, 3 and 4 only. Visible Light Communication Technology It is a wireless method that enables high-speed transmission of data with visible light. It makes use of Visible Light spectrum. It occupies the spectrum from 380 nm to 750 nm. Hence statement 1 is correct. It enables high-speed internet access primarily in the indoor environment. It works on the principle of intensity modulation of existing solid-state lighting infrastructure often provided by light-emitting diodes. The data is transmitted by modulating the intensity of light given off by a light source and the signal is received by a photodiode device that transforms the data into forms that are readily-consumed by end-users. VLC systems operate at optical frequencies and emit no electromagnetic interference. Therefore, it can be used in Healthcare services. Hence statement 4 is correct. Advantage of this technology- The size of the visible light spectrum which is 10,000 times larger than the entire radio spectrum. Light travels 186,000 miles per second, which is much faster than the 344 meters per second travelled by radio waves in air. The nature of light is that it is unable to pass through opaque walls. Hence, VLCT is used in indoor environment/short range. Hence statement 2 is not correct. Li-Fi stands for Light-Fidelity. It is a technology under VLCT. It can transmit enormous amounts of data through LEDs (Light Emitting Diodes). Li-Fi can transmit large amounts of data faster than Bluetooth and wi-fi. Hence statement 3 is correct.