lets first try with n=9 ( our tarhet is to get only top three teams get 9 points . If more than three teams will get 9 points then choosing top three will also depend upon referee )
A wins over D,E,F,G and ties with B so total 9 points
B wins over D,E,F,G and ties with A so total 9 points ( if A ties with B then B also ties with A)
now try for C to getting 9 points so first three(A,B,C) will qualify for next round
C ties with D (1 point) , wins over E,F,G( 6 points ) , no other possibilities for C
hence with 9 points we cant choose top three teams guarantely.
Now n=10
A wins over D,E,F,G and ties with B,C so total 10 points
B wins over D,E,F,G and ties with A,C so total 10 points
C wins over D,E,F,G and ties with B,A so total 10 points
for others ( D,E,F,G) we cant get 10 points
Hence 10 is the minimum total number of points a team must earn in order to be guaranteed a place in the next round.
ANS is D