To determine the congruence between the triangles, we compare their side lengths.

Let's list the sides of $\triangle ABC$ and try to match them with the sides of $\triangle DCB$.

• Side $AB = 5 \text{ cm}$ in $\triangle ABC$.

• Side $DC = 5 \text{ cm}$ in $\triangle DCB$. So, $AB = DC$.

• Side $BC = 4 \text{ cm}$ in $\triangle ABC$.

• Side $CB = 4 \text{ cm}$ in $\triangle DCB$. So, $BC = CB$.

• Side $AC = 8 \text{ cm}$ in $\triangle ABC$.

• Side $DB = 8 \text{ cm}$ in $\triangle DCB$. So, $AC = DB$.

Since all three corresponding sides of $\triangle ABC$ are equal to the three corresponding sides of $\triangle DCB$, the triangles are congruent by the SSS (Side-Side-Side) congruence criterion.

To write the congruence statement, we need to match the vertices correctly based on the equal sides:

• Since $AB = DC$, vertex A corresponds to vertex D, and vertex B corresponds to vertex C.
• Since $BC = CB$, vertex B corresponds to vertex C, and vertex C corresponds to vertex B.
• Since $AC = DB$, vertex A corresponds to vertex D, and vertex C corresponds to vertex B.

Combining these, we get the correspondence:

• A $\leftrightarrow$ D
• B $\leftrightarrow$ C
• C $\leftrightarrow$ B

Therefore, the correct congruence statement is $\triangle ABC \cong \triangle DCB$.

(1) $\triangle ABC \cong \triangle DBC$, by SAS - Incorrect vertex correspondence and criterion.
(2) $\triangle ABC \cong \triangle DCB$, by SAS - Incorrect criterion.
(3) $\triangle ABC \cong \triangle DBC$, by SSS - Incorrect vertex correspondence.
(4) $\triangle ABC \cong \triangle DCB$, by SSS - Correct vertex correspondence and criterion.

The final answer is $\text{4}$.