4,7,15,31,35,19,11,?  Choices:
A) 5	B) 6	C) 7	D) 8	E) 9
Find the diff between each digits:   7-4= 
<gadget id="calculator">7-4</gadget>
<output>3</output>
3   15-7= 
<gadget id="calculator">15-7</gadget>
<output>8</output>
8   31-15= 
<gadget id="calculator">31-15</gadget>
<output>16</output>
16   35-31= 
<gadget id="calculator">35-31</gadget>
<output>4</output>
4   19-35=-16   11-19=-8   i.e. it shows a series 3,8,16,4,-16,-8,-3   that means next digit would be 8.   ANSWER:8
<result>D</result>
4,7,15,31,35,19,11,?