When denominators are equal, the fraction with the largest numerator is the greatest.<br><br>
&bull; All denominators are 5.<br>
&bull; Compare numerators: 3, 1, 2, 4. Largest numerator = 4.<br>
&bull; \( \frac{4}{5} \) is the greatest fraction.<br><br>
Final Answer: D: \( \frac{4}{5} \)