Julia is watching a Tom Cruise movie, there are four answers:-
1.It is very good - Il est très bon - agreed
2.He is very good - Il est très bon - Only if you are referring to Tom Cruise
3.She is very good - Elle est très bonne - Julia might not like Tom Cruise so she might be very good in watching it............
4.I can't remember the last answer offhand but it does have an instance where it COULD be correct.
The point is that other than answer 1 the other options are ALL options and may all be correct in certain circumstances. The ONLY certain answer to this particular question is the first one, all others are possible but are liable to return a partially correct result depending upon the way in which the question is viewed. I submit that it may NOT be the best question for this exercise.