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Project differs from Select in that
AProject keeps every column but drops rows that fail a predicate
BProject joins R against itself on shared attributes
CProject renames every attribute of R to A1, A2, A3...
DProject keeps every row but emits only the named columns
Answer & Solution
Correct answer: D. Project keeps every row but emits only the named columns
Select (σ) trims ROWS, project (π) trims COLUMNS. Different axes. The other options describe Select (option A), a self-join (B), or a rename (C); none of them is project.
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