+1 are two extreme points of the function f(x)=ax3+bx2+cx+d;

That is, 1 is two zeros of the derivative function f'(x)=3ax2+2bx+c;

According to the image, when x∈(-∞,-1) and f ′ (x) > 0, then the image of the function f ′ (x) should be upward, so the derivative function image is as follows:

As can be seen from the figure, the solution set of f'(x)x > 0 is: (-1, 0)∞( 1, +∞),

So the answer is d.