Question: Relational projection removes columns from a relation. Why can this have the side effect of changing the number of rows or tuples in the relation?

Relational projection removes columns from a relation. Why can this have the side effect of changing the number of rows or tuples in the relation?
Since tuples are filtered during column removal, you can have fewer tuples after the projection.
Column removal can result in additional tuples being added to the relation.
Correct!
Column removal can result in duplicate tuples, which are then collapsed to a single tuple.
All of the tuples with the new set of columns are added to the relation, changing the number of tuples (adding to them).

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