choosing a leader

[jasen]

At a class, the students are going to choose a leader.
The class has 3 groups of students.
Each group contains 4 students.
so total students are 12.
After discussion, they determine this rule :

each students have to vote 1 from each group.
so each students have to vote for 3 persons.
example: if the groups are [a,b,c,d] [e,f,g,h] [i,j,k,l]
each student have to choose 1 from [a,b,c,d], 1 from [e,f,g,h], and 1 from [i,j,k,l]

If someone break the rule, his votes is disqualified.

(To simplify the problem, lets write just initials of the students,
since there is no 2 students has same initials)

here are the votes

 1. [c,d,f]     2. [a,g,c]     3. [d,h,l]    4. [b,e,d]     
 5. [f,j,g]     6. [g,j,i]     7. [j,i,a]    8. [j,a,f]
 9. [b,h,k]     10.[l,c,d]     11.[a,h,l]    12.[g,e,b]

there is 1 vote is disqualified.

The Questions :

• Determine each group members
• Determine which vote is disqualified.

[Bashele]

[lfbi] [adgk] [cjeh] disq-d voice 2

[sushma]

Group member :

(A D G K)

(B F I L)

(C E J H)

disqualified vote is 2nd one he is voting to [A, C, G] where  A & G belongs to same group.