In prehistoric times, communication with the spiritual world is thought to have been largely conducted in

The answer for this question is: Caves
This knowledge is supported by the findings that archeologists found on the wall of the caves. Where a lot of scripture, pictures of the ceremonial process, and several ceremonial artifacts were found which support the conclusion that Prehistoric people see caves as a worthy enough place to perform their daily religious rituals.

A, c, and d are the answers