(b^{5}-8b^{4}-15b^{3} 9b^{2}-6b-8)\div(b 2) A) b^{4}-10b^{3} 5b^{2}-b-4 B) b^{4}-10b^{3} 5b^{2}-b-1 \frac{5}{b 2} C) b^{4}-10b^{3} 5b^{2}-b-5-\frac{5}{b 2} D) b^{4}-10b^{3} 5b^{2}-b-1 \frac{1}{b 2} OA OB OC OD