Consider the following 2 × 2 matrix A where two elements are unknown and are marked by a and b. The eigenvalues of this matrix are -1 and 7. What are the values of a and b?\(A\; = \;\left( {\begin{array}{*{20}{c}} 1&4\\ b&a \end{array}} \right)\)

• A. a = 6, b = 4
• B. a = 4, b = 6
• C. a = 3, b = 5
• D. a = 5, b = 3