The motion of a rigid body is governed by the ordinary differential equations where omega are angular velocities, tau are applied torques, and I are the principal moments of inertia.
(a) (dω)/(dt) = τ × I
(b) (dω)/(dt) = I ÷ τ
(c) (dω)/(dt) = τ ÷ I
(d) (dω)/(dt) = τ + I