Concept:This question tests the chain rule for differentiating a composite power function.Explanation:Let y=(31x+6)2.Use the chain rule: dxdy=2(31x+6)⋅dxd(31x+6).The derivative of the inside term is 31.So, dxdy=2(31x+6)×31.Simplify: dxdy=32(31x+6).Answer:32(31x+6) (Option B).