There are ____________ ways you can reach the conference hall, but the tram service in this city is excellent.

The correct choice, "various," effectively fits the context of the sentence by conveying the idea that there are multiple distinct methods available to reach the conference hall. The word "various" is an adjective that describes the multitude of ways or options one might consider, emphasizing diversity and a range of alternatives.

Using "various" here suggests that the speaker is highlighting an assortment of possible routes or transport methods, which aligns well with the mention of the excellent tram service, indicating that there are indeed diverse choices available for attendees.

In contrast, other options do not fit as appropriately. "Varying" implies a change or fluctuation over time and does not convey the intended meaning of multiple options. "Varieties" refers to different forms or kinds but is not typically used to describe ways to do something; it would be more relevant in a context discussing types of items or species. "Varied," being an adjective describing something that is diverse or changed, does not work in this context without a noun to modify. Therefore, "various" is the most suitable choice to indicate a number of different options.