The equation X(t)=t⁴ -5 t² + 6 gives the position of a comet relative to a fixed point, measured in millions of miles, at time t , measured in days. Solve the equation X(t)=0 . At what times is the position zero?
(A) 2,3 (B) -2,-3 (C) ±2, ±3 (D) ± √2, ±√3