The maximum value of \(\sin \left( {{\rm{x}} + \frac{{\rm{\pi }}}{6}} \right) + \cos \left( {{\rm{x}} + \frac{{\rm{\pi }}}{6}} \right)\) in the interval \(\left( {0,\frac{{\rm{\pi }}}{2}} \right)\) is attained at

• A. \(\frac{{\rm{\pi }}}{{12}}\)
• B. \(\frac{{\rm{\pi }}}{6}\)
• C. \(\frac{{\rm{\pi }}}{3}\)
• D. \(\frac{{\rm{\pi }}}{2}\)