a, b, c are the lengths of three sides of a triangle ABC. If a, b, c are related by the relation a + b + c = ab + bc + ca, then the value of sin A + sin B + sin C is

• A. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center">4</td></table>
• B. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3 <span style=" text-decoration: overline;">3</span></center></td><td rowspan="2"></td></tr><td align="center">2</td></table>
• C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"></td></tr><td align="center">2</td></table>
• D.
• E. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>9</center></td><td rowspan="2"></td></tr><td align="center">4</td></table>