The answer is the third option, \(\{ x | x \leq 7\}\).
They're asking you to find the union of the two sets of numbers, set \(A\) and set \(B\).
Set \(A\) contains all numbers less than \(5\).
Set \(B\) contains all numbers less than or equal to \(7\).
The union of both sets will include the numbers in both of the sets altogether, or \((A + B)\). Since any number less than \(5\) (from set \(A\)) is already contained in all numbers less than \(7\) (from set \(B\)), you can just write your final answer as set \(B\), which is \(\{ x | x \leq 7\}\).
Hope that makes sense!
