The following linear system is in echelon form. Solve the linear system by back substitution. ×₁-5x2+x3 = 18 X2+x3 = 8 ... What is the solution to the linear system? Select the correct choice below and, if necessary, fill in the answer box(es) to complete your choice. A. There is a unique solution, X₁ = 1×2 = (Type integers or simplified fractions.) X3 = B. There are infinitely many solutions of the form x₁ = t is a real number. ' 1×2 = ,X3=t, where (Simplify your answers. Use integers or fractions for any numbers in the expressions.) C. There are infinitely many solutions of the form x₁ = and t are real numbers. X2S, x3 =t, where s (Simplify your answers. Use integers or fractions for any numbers in the expressions.) D. There is no solution.