I think there needs to be an explanation here of what "marshrutka" is for those who do not live in Ukraine (or other countries where this concept exists). "Marshrutka" is something between a public bus and a taxi (full name is "marshrutnoe taxi" - taxi with a route). It is a private mini bus, which usually costs more than a regular bus, but is faster. It has a number and a route it follows, but you can get on and off anywhere you want. In Israel this is called "sherut"
Bus is автобус.
I know what a маршрутка is, but "bus" shouldn't be marked wrong if "city bus" is a definition. In English, a bus and a city bus are the same thing physically. Maybe one drives long distances city-to-city while the other makes stops within a city, but they're the same vehicle. A маршрутка, however, is usually a van that seats less than twenty passengers. Maybe a better definition would be "passenger van" or "shuttle."
I think "minibus" works just fine, and that was one of the options. Certainly in British English, "passenger van" wouldn't work - it just isn't an expression that's used (haven't heard it in other Englishes either), and neither does "shuttle" - that would be a dedicated express service usually serving just one destination (so picks up passengers going to there, and only drops off on the way back, serving an airport or a major event), but could very well be a full size double-decker bus. Perhaps the accepted answers should be just "minibus" or "marshrutka".
I like "minibus" as a translation very much! The only problem is that I wouldn't imagine anyone saying, "I'm taking the minibus to work today," just as nobody would use "passenger van" that way. The point is that "bus" shouldn't be marked wrong in this exercise. They're trying to differentiate between a bus and a city bus when in English a "city bus" is a bus.
I live in the city of Calabasas, California, and our busses are a slightly bigger version of a Ukrainian маршрутка but smaller than a full автобус. It's called the Calabasas Shuttle even though it services the whole town.
Ah, the wonders of the differences between Englishes! In Britain I have never heard the phrase "city bus". Local bus services that stop frequently and you don't pre-book and you pay the driver when you get on - whether in a town, city or rural area - would just be a "bus". The ones that run between towns, and that generally can be pre-booked, would be a "coach". So I think we're back to a translation as "minibus".
I have never heard the collocation "share taxi" (as a noun) in English... You can say "We are going to share a taxi" OR "I shared a taxi" OR "We are sharing a taxi"... As a verb only.... As noun things like "shared taxi, shared room" etc. Are possible.... "Marshrutka" is not a synonym for "taxi"... It is definitely not interchangeable in English... Furthermore I have been living in Kiev for 3 years and I have never heard anybody call a Marshrutka a taxi or vice-ve sa.... A Marshrutka is a Marshrutka!!!