The correct answer is: a) Scenic transportation up the mountainside.
Ropeway services in Sikkim, like the one in Gangtok, offer scenic transportation up the mountainside. They are a popular tourist attraction and offer stunning views of the surrounding mountains and valleys. The ropeways are also a convenient way to get around the city, as they provide access to many of the popular tourist destinations.
Option b) is incorrect because ropeway services are not used for cargo transportation. Option c) is incorrect because ropeway services are not a quick commute to higher altitudes. Option d) is incorrect because ropeway services are not used for long-distance travel.