2,5,12,31,81,__  Pick.
A) 210 B) 211 C) 213 D) 214 E) 215
12= 5*2+2   31= 12*2+5+2   81= 31*2+12+5+2   Similarly 81*2+31+12+5+2 = 162+50= 
<gadget id="calculator">162+50</gadget>
<output>212</output>
212   ANSWER:213
<result>C</result>
2,5,12,31,81,__