Gave wrong answere at the Video Interview with Home Office

Hi I just had an interview today with the HO for my tier 4 visa. During the interview The interviewer asked me about duration of the coure and I answered 3 years (and my course is actually 5 years as I do PhD), which is wrong and I dont know why I made such a stupid mistake (. Everything went well acept for that bit. So will my application be rejected? Im so sickly worried over here (. Did anyone have the same problem? Please advice me (

I think you are perhaps overthinking it.
Very few interviews are perfect, errors and inaccuracies do happen. You are dealing with nervous people and human error on both sides happens.
If that was your only concern I am positive you will not be classed as a non-genuine student for that minor mistake.

Good luck