Gas flows from left to right through this pipe, whose interior is hidden. The pipe is connected to water tubes at bottom $1,2,$ and $3$ positions. At which point does the pipe have the smallest inner diameter?

Question $11$ options:

A$.$ Point $1$

B$.$ Point $2$

C$.$ Point $3$

D$.$ The diameter doesn't change.

E$.$ There is not enough information to tell.