Answer:
c. Mobile hotspot
Step-by-step explanation:
A mobile hotspot is a hotspot that is to be activated by turning on the WiFI hotspot. It is used to share the cellular data to the laptop, computer system and the mobile devices who do not have an internet connection
Since in the question, it is mentioned that the one traveler has an unlimited cellular data plan and a consistent strong signal
So the mobile hotspot should be used to provide internet service to the group.