What is \(\mathop \smallint \limits_{\frac{1}{3}}^1 {\rm{f}}\left( {\rm{x}} \right){\rm{dx}}\) equal to?

• A. \(\frac{{37}}{{72}}\)
• B. \(\frac{2}{3}\)
• C. \(\frac{{17}}{{72}}\)
• D. \(\frac{{37}}{{144}}\)