Use Descartes' Rule of Signs to find the number of possible positive real roots and the number of possible negative real roots for the function f(x) = x^4+ 2x^3-3x^2- 8x - 4. a positive 1; negative 3 or 1

b. positive 1; negative 3 or 5

C. positive 3; negative 3 or 1

d. positive 3; negative 3 or 5