4. A man of mass m falls from rest at point A that is at a horizontal distance of D from the origin O of an xyz coordinate system, i.e., A = (D, 0, 0). Assuming gravity \( \vec{g} = -g\hat{z} \). What is the angular momentum of the falling man about O at time t?
(A)\( Dmgt\hat{x} \)
(B)\( \frac{1}{2}Dmgt\hat{x} \)
(C)\( Dmgt\hat{y} \)
(D)\( \frac{1}{2}Dmgt\hat{y} \)

(E)\( -\frac{1}{2}Dmgt\hat{z} \)

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