I go to work by .............................-by underground.

[ali7772016]

I go to work by .............................
a-by the underground



b-by underground.
I prefer "b"by underground.
What do you think?

 

[GoesStation]

Neither is correct because the word by would be repeated in both cases. Assuming one of the bys is a misprint, A is better. More naturally, say I go to work on the Underground.