To simplify the expression \( a^{67}b^{34} \), we need to consider whether we can factor or combine any terms. However, since both the terms \( a^{67} \) and \( b^{34} \) do not have any common bases or exponents that can be simplified, the expression is already in its simplest form.
None of the simplifications proposed in your options (like \( 23 \), \( ab^{33} \), or \( a^{33} \)) are correct representations of \( a^{67}b^{34} \).
Thus, the correct answer is:
a67b34