Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[Q]: sandpaper is a piece of paper with an abrasive glued to it.
[A]: sandpaper


[Q]: the castle of almansa is a castle in almansa, spain.
[A]: castle of almansa


[Q]: child development refers to biological, psychological and emotional changes that happen in humans between birth and the end of adolescence, at which time the individual goes from dependence to independence.
[A]:
child development