Use row operations to solve the system. x + y - z=1 4x - y + z = 9 x - 3y + 2z = -15 Select the correct choice below and fill in any answer boxes within your choice. A. There is one solution. The solution is (). (Type an exact answer in simplified form.) B. There are infinitely many solutions. The solutions are (z), where z is any real number. C. There is no solution.