We have sent several spacecraft on trajectories that will ultimately take them into interstellar space (pioneer 10 and 11, voyager 1 and 2, new horizons). how long will it take these spacecraft to travel as far as the nearest stars?

The closest star to our solar system is the Proxima centauri (divided into Alpha century A and Alpha century B).
It will take 4.367 light years to reach those stars. Which is 4.122 × 10^13kilometres.
Meaning it will be years before those spacecraft reach them.

The answer would be  b. hope this !