True or false? If false, correct the statement. Recursive functions: 1. often have fewer local variables than the equivalent nonrecursive routines. 2. generally use while or for statements as their main control structure. 3. are possible only in languages with static storage allocation. 4. should be used whenever execution speed is critical. 5. are always shorter and clearer than the equivalent nonrecursive routines. 6. must always contain a path that does not contain a recursive call. 7. are always less efficient, in terms of Big-O complexity.