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SELECT operation in SQL is equivalent to

  1. The selection operation in relational algebra
  2. The selection operation in relational algebra, except that SELECT in SQL retains duplicates
  3. The projection operation in relational algebra
  4. The projection operation in relational algebra, except that SELECT in SQL retains duplicates
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Option D is correct because SELECT operation in SQL is equivalent to The projection operation in relational algebra, except that SELECT in SQL retains duplicates but projection gives only distinct. 

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The SELECT operation in SQL is equivalent to the selection operation in relational algebra.

The SELECT operation in SQL is used to retrieve specific columns and rows from a table in a relational database. This operation is similar to the selection operation in relational algebra, which is used to select a subset of rows from a relation based on a specified condition.

Both SELECT in SQL and selection in relational algebra retain duplicate rows when they are selected, and the SELECT operation in SQL does not eliminate duplicates.

The projection operation in relational algebra is used to select a subset of columns from a relation, which is not the same as the SELECT operation in SQL.
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