The intersection is a set operation and set doesnt contain duplicate values. $\text{Q1}$ will print all the rows including those which are duplicates i.e there may be some rows in its output that might be repeated. In $\text{Q2}$ duplicate rows are printed only once i.e there will be no repetition. $\text{Q2} \leq \text{Q1}$ and hence result of $\text{Q2}$ will always be contained in $\text{Q1}$.
If it would have been INTERSECT ALL then the answer would have been (A).
