The answer is D. Palace.
A house is a building for human habitation, especially one that is lived in by a family or small group of people. A cottage is a small house, typically in the countryside. A school is an institution where children are educated. A hut is a small, simple dwelling, typically made of mud, wood, or stone. A palace is a large, grand house, especially one belonging to a monarch or other high-ranking person.
The word “palace” is different from the rest of the words in the list because it is the only word that refers to a building that is not typically used for habitation. Palaces are typically used for official purposes, such as hosting meetings or entertaining guests.