What technology allows many smartphones to act as hotspots?

The correct answer is Wi-Fi, as it is specifically designed for wireless local area networking and allows devices to connect to the internet without physical connections. When a smartphone utilizes its Wi-Fi capabilities to act as a hotspot, it shares its mobile data connection with other devices, enabling those devices to access the internet through the smartphone. This functionality is commonly referred to as "tethering," where the smartphone creates a Wi-Fi network that other devices can join, much like a traditional wireless router.

Other options, while related to mobile and wireless technology, do not serve the same function as Wi-Fi in hotspot creation. Bluetooth is primarily used for short-range communication between devices but does not facilitate internet sharing effectively over long distances. 5G technology refers to the mobile network standard that provides improved speed and performance but is not directly involved in the hotspot functionality of smartphones itself. NFC (Near Field Communication) is used for very short-range communication, typically for quick data transfers or contactless payments, and does not support network sharing like a Wi-Fi hotspot.