Step 1: Understand the Wurtz reaction.
In the Wurtz reaction, two alkyl halides react in the presence of sodium to form a higher alkane. In this case, the reaction leads to the formation of \( \text{C}_8\text{H}_{10} \), which is the expected product.
Step 2: Conclusion.
Thus, the product of the Wurtz reaction for \( \text{C}_6\text{H}_4\text{Br} \) is \( \text{C}_8\text{H}_{10} \).
Final Answer:
\[
\boxed{C}
\]