27.
Which of the following are correct in respect of the system of equations \( x + y + z = 8 \), \( x - y + 2z = 6 \) and \( 3x - y + 5z = k \)?
1. They have no solution, if \( k = 15 \).
2. They have infinitely many solutions, if \( k = 20 \).
3. They have unique solution, if \( k = 25 \).
Select the correct answer using the code given below.