Which equation is quadratic in form?
A8x^5 + 4x^3 + 1 = 0
B10x^8 + 7x^4 + 1 = 0
C9x^16 + 6x^4 + 1 = 0
A8x^5 + 4x^3 + 1 = 0
B10x^8 + 7x^4 + 1 = 0
C9x^16 + 6x^4 + 1 = 0