Use Vieta's formula for x² + px + q = 0. For this form, the sum of the roots is -p and the product of the roots is q. The given roots are -5 and -3, so their sum is -5 + -3 = -8. Since sum = -p, we have -p = -8, which gives p = 8. The product -5×-3 = 15 also matches the constant term, so the roots are consistent. Therefore the correct answer is 8.