The open-loop transfer function of a control system is given by

\[
\frac{\mathrm{K}(s+10)}{s(s+2)(s+a)}
\]

The smallest possible value of ' \(a\) ' for which this system is stable in the closed-loop for positive values of \(\mathrm{K}\) is
(a) 0
(b) 8
(c) 10
(d) 12