Concept:A set and its complement have no common elements, so their intersection is the empty set.Explanation:For any set P, we have P∩P′=∅. Similarly, for set Q, we have Q∩Q′=∅. Now, (P∩P′)∪(Q∩Q′)=∅∪∅. The union of two empty sets is also empty. So, (P∩P′)∪(Q∩Q′)=∅.Answer:∅, which is option A.