Let us go through the answer choices
(A) Whether users of the app also engage in regular physical exercise apart from using the app
The question specifically refers to the app's reminder system as the primary reason for weight loss. We are not really interested in all the factors that could have contributed to weight loss rather its efficacy.
(B) Whether other similar nutritional tracking apps also show similar results in terms of user weight loss
Again, this is outside of the scope of what is needed to evaluate the developper's argument. We are not evaluating whether the technology used is the most cutting-edge on the market or how it fares against competitors, but rather, 'is it efficient at doing its inteded purpose?'
(C) Whether the users had tried other diet methods before using the app and had not seen similar weight loss results
We are not talking about diets as a whole but the specific app's reminder system. This is a specific feature within the app as a whole. There may be other features to the app that may also influence weight loss, but we want to evaluate the efficacy of the specifc system.
(D) Whether the reminders from the app are more effective at altering eating habits compared to other features of the app
This answer choice would actually evaluate the developers' argument since it is comparing the feature that is the "primary reason for this weight loss success" against the other features of the app.
(E) Whether users continue to lose weight or maintain weight loss after the initial six months of using the app
This falls outside of the scope of what they are looking to evaluate. We are determining if the app's feature was the primary reason for weight loss after six months of use, not whether the the users picked up good habits that enabled them to carry on on their fitness and health journeys.
The answer is D
Bunuel
A new smartphone app that encourages healthy eating by tracking daily nutrient intake has reported significant user weight loss after six months of use. The developers claim that the app’s reminder system, which prompts users to record their meals and snacks, is the primary reason for this weight loss success.
In evaluating the developers' argument, it would be most important to determine which of the following?
(A) Whether users of the app also engage in regular physical exercise apart from using the app
(B) Whether other similar nutritional tracking apps also show similar results in terms of user weight loss
(C) Whether the users had tried other diet methods before using the app and had not seen similar weight loss results
(D) Whether the reminders from the app are more effective at altering eating habits compared to other features of the app
(E) Whether users continue to lose weight or maintain weight loss after the initial six months of using the app