Final answer:
The correct protocol that operates at 2.4 GHz with a bandwidth of 1 or 2 Mbps is 802.11b.
Step-by-step explanation:
The protocol that operates at 2.4 GHz and has a bandwidth of 1 or 2 Mbps is 802.11b. The other options provided represent different standards: 802.11 is the original Wi-Fi standard which is now considered obsolete, 802.11a operates in the 5 GHz band, and 802.11g operates at 2.4 GHz but with a higher bandwidth of up to 54 Mbps. Therefore, the correct answer is C. 802.11b.