A SIM card enables a laptop to connect directly to a cellular network when the laptop includes an integrated mobile broadband (cellular) modem (often referred to as LTE/5G capable). In this setup, the SIM provides subscriber identity and authentication details required by the carrier, allowing the laptop to register on the cellular network and access mobile data without relying on separate tethering devices. This aligns with CompTIA A+ Core 1 coverage of mobile and wireless connectivity options, including cellular data capabilities and the components required to use them.
The other options do not meet the requirement "without using an external device" for cellular connectivity. A hotspot typically means using a phone or dedicated hotspot device to share its cellular connection over Wi-Fi, which relies on an external device. Bluetooth can be used for tethering, but it still requires a phone providing the cellular connection. NFC is used for short-range communication like tap-to-pair or payments and does not provide cellular internet access. Therefore, a SIM card (with an internal cellular modem) is the correct choice.