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Given relations $R(w,x)$ and $S(y,z),$ the result of  SELECT DISTINCT $w,x$ from $R,S$

  1. $R$ has no duplicates and $S$ is non-empty
  2. $R$ and $S$ have no duplicates
  3. $S$ has no duplicates and $R$ is non-empty
  4. $R$ and $S$ has the same number of tuples
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