A passenger within a bus during the trip on their way to Amsterdam asks the driver:
a. How many kilometers left to Amsterdam?
b. How many kilometers have been left to Amsterdam?
c. How many kilometers do we have ahead to Amsterdam?
Added: I think "b" and "c" mean the same and the both sound quite idiomatic to me, and although I have encountered some other examples like "a", still it doesn't sound grammatically correct to me while we are talking about 'future' and the 'simple past tense' doesn't seem to be a proper tense here. However, still I have my doubts whether I am right or wrong about it.
Hence, I am wondering which sentence is correct. If there is any wrong choice, please let me know which one it is and why?