5. As shown in the figure, in $\triangle A B C$, $D, E$ are the trisection points of $B C$, $M$ is the midpoint of $A C$, and $B M$ intersects $A D, A E$ at $G, H$. Then $B G: G H: H M$ equals ( ).
(A) $3: 2: 1$
(B) $4: 2: 1$
(C) $5: 4: 3$
(D) $5: 3: 2$
5. $\mathrm{D}$ (Hint: Draw $M N / / B C$ through $M$,

it can be obtained by the median theorem or Menelaus' theorem. Note: When the trisection points become 4, 5, or $n$ equal parts, what results can you get?)