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In the following class diagram, which functionality is missing? DataBaseReader +open:void +close:void +go ToFirst:void +go ToLast:void +howMany Records:int +are ThereMore Records:boolean +position Record:void +getRecord:String +getNextRecord:String Select one or more: a. Position the cursor in the first record b. Add a record to the database C. Retrieve a record from the database d. Calculate the number of records in the database