If it helps, any time you choose "No effect", you're making a guess about how thorough the experiment was, not about the program itself. Every program will have

If it helps, any time you choose "No effect", you're making a guess about how thorough the experiment was, not about the program itself. Every program will have some effect, but may be too small to have been detected. Similarly if the correct answer is "no effect" that just means the studies weren't accurate enough.