Final answer:
The effectiveness of aspirin gradually decreases over time due to hydrolysis. Based on the provided data, it takes approximately 4 hours for aspirin to lose its effectiveness.
Step-by-step explanation:
The effectiveness of aspirin gradually decreases over time due to a process called hydrolysis. Hydrolysis is the reaction of aspirin with water molecules, which breaks down the chemical structure of aspirin. Based on the hydrolysis data, the graph shows the concentrations of aspirin and salicylic acid over time. From the graph, we can observe that after approximately 4 hours, the concentration of aspirin decreases significantly, indicating a loss of effectiveness. Therefore, the correct answer is d) 4 hours.