Acaravan was a group of people who a. lived in the desert as a nomadic tribe b. frequently traded goods with one another c. were sent by trading posts to assist travelers d. traveled together across the desert for safety reasons

They traveled together across the desert for safety reasons, the answer is D. This is because the desert is dangerous and there is a lack of resources to sustain life. Resources must be shared and conserved for the travel as they are not readily available. They rely on one another until they reach as oasis or somewhere that is inhabitable.