<h3>
Answer: C. Empty set</h3>
Explanation:
The first set {x | x < -3} means we're talking about numbers smaller than -3. This includes -4, -5, -6, etc
The second set {x | x > 5} means we're talking about numbers larger than 5. So things like 6,7,8,...
Combining both at the same time, we want to find a number that is both smaller than -3 and larger than 5. This is impossible as no such number exists. You can pick one or the other, but not both.
There are no solutions. Since there are no solutions, the solution set is the empty set.