What is the name of a structure or room used to hold cremated remains within a mausoleum?

The term "columbarium" refers specifically to a structure or room designed to hold the cremated remains of individuals. Typically found within a mausoleum, a columbarium features niches or compartments where urns containing ashes can be placed. This serves as a dignified way to store and memorialize those who have been cremated.

The other options relate to different aspects of funeral or memorial practices. A chapel is generally a place for ceremonies, while a chancel refers to the area around the altar in a church. A committal service is the ceremony held at the time of burial or cremation, focusing on the formal aspect of committing the remains to their final resting place. None of these options serve the specific purpose of housing cremated remains like a columbarium does.