Answer:
Van
Explanation:
Van refers to both the Aunt and Uncle as "they", they go to the mountains. All the other forms of ir refer to either I, he/she, you, we, etc.
In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe.
The answer could be Fue or Era
