They want to know whether it took longer than the planned 4 years for you to graduate and, if so, why. Nothing more.
So if you took 6 years to graduate and it was because you did a couple of years of research...yes, your training was interrupted, and that's cool.
If it took you 6 years to graduate and it was because you were in prison for two years...yes, your training was interrupted, and that's going to be a bit of a problem for you.