Kon W Save response Question 2 10 points Save Answer Relation R(a, b) has no duplicate tuples, although neither a nor b is a key. Relation S(c may have duplicates. Which of the following queries is guaranteed to produce no duplicates? O a SELECT cd WHERE EXISTS (SELECT a, b FROM R WHERE a CAND b d) Ob SELECT d WHERE (c, d) IN (SELECT a, b FROM R); O c SELECT a FROM R O d SELECT c, d FROM RS WHERE a d AND b A Moving to another question win save this response. &51 PM A