Select either true or false for each of the following questions. a) each relation can have multiple clustered or unclustered indexes. b) a relation can have a clustered index on a set of attributes. c) each relation can have multiple indexes using alternative 1 d) range queries cannot be answered using hash indexes. e) maintaining clustered indexes are more expensive than sorted files. f) index-olny plans work equally efficiently with unclustered indexes. g) in any index file the data records are sorted by the search keys