For the initial conditions x1 (0) = x2 (0) = 1, the response x(t) for the zero-input response is:

a. x1 (t) = (1 + t), x2 (t) = 1 for t  0

b. x1 (t) = (5 + t), x2 (t) = t for t  0

c. x1 (t) = (5t + 1), x2 (t) = 1 for t  0

d. x1 (t) = x2 (t) = 1 for t  0