\(\left( {x - 3} \right)\left( {7 - x} \right) \ge 0\)
A.\(x \in \left\{ {4;\,\,5;\,\,6;\,\,7} \right\}.\)
B.\(x \in \left\{ {3;\,\,4;\,\,5;\,\,6;\,\,7} \right\}.\)
C.\(x \in \left\{ {4;\,\,5;\,\,6} \right\}.\)
D.\(x \in \left\{ {3;\,\,4;\,\,5;\,\,6} \right\}.\)