To simplify the expression \( a^{67} b^{34} \), we first identify that it consists of two parts: \( a^{67} \) and \( b^{34} \).
Since there are no like terms or common bases in this expression, we cannot combine the terms further. Therefore, the simplified form remains:
\[ \frac{a^{67}}{b^{34}} \]
So the correct response is:
\[ \frac{a^{67}}{b^{34}} \]