Correct option is A
The Gotthard Base Tunnel, located in Switzerland, was officially opened in June 2016. This tunnel is the longest and deepest rail tunnel in the world, stretching a remarkable 57 kilometers (35 miles) and running under the Swiss Alps. It took nearly two decades to construct and represents a significant engineering achievement. The tunnel allows faster and more efficient travel between northern and southern Europe, significantly cutting travel times and improving freight movement across the continent. The Gotthard Base Tunnel is a vital part of Switzerland’s transportation infrastructure.
