Select the option that can be used as a one-word substitute for the given group of words.
An area/place in which dead bodies are buried

The correct option is Cemetery.

Let's break down the meaning of the given group of words and analyze each of the options to understand why "Cemetery" is the correct one-word substitute:
Given group of words: "An area/place in which dead bodies are buried"

1. Cemetery: A cemetery is a large burial ground, especially one that is not in a churchyard. This matches the definition of a place where dead bodies are buried perfectly.
2. Demise: This word refers to a person's death or the end/failure of an institution, event, or relationship. It describes the state or event of dying, not the physical place of burial.
3. Mansion: A mansion is a large, impressive, and stately house. It is a residence for the living, not a burial place.
4. Clementi: This is typically a proper noun (often referring to a composer, Muzio Clementi, or a place/district name like Clementi in Singapore) and has no relation to burial grounds or death.

Therefore, Cemetery is the appropriate one-word substitute for the given description.