A database index consists of one or more keys and is related to the specific tables. It allows a query to retrieve data efficiently from a database. As a database index increases the speed of data retrieval, it is required to define correct indexes for each table.
Option A is incorrect. A database index allows a query to retrieve, not delete data efficiently from a database.
Option B is correct. A database index allows a query to retrieve data efficiently from a database.
Option C is incorrect. A database index allows a query to retrieve, not find data efficiently from a database.
Option D is incorrect. A database index allows a query to retrieve, not search for data efficiently from a database.