Hola Timothy

Thank you for reaching out and providing the details of the question you encountered.

It appears that the question was designed to test knowledge of conditional sentences in Spanish, specifically when to use "si" (if) to introduce a condition. The correct answer to the question is "Si eres alérgico a las nueces, no pruebes ese pastel", which translates to "If you are allergic to walnuts, don't try this cake."

The confusion seems to stem from the use of "cuando" (when) which implies a time or occurrence, rather than a condition. "Cuando" would not be appropriate in this sentence because we are talking about a conditional situation, not a specific time or habitual action.

If the mini lesson provided was meant to explain the use of "si" for conditional sentences and "cuando" for time-related sentences, and this was not clear, we apologize for the confusion. For future reference, remember that "si" is used to set a condition that must be met, whereas "cuando" is used to refer to the time when something occurs.

Please let me know if there's anything else we can clarify or assist you with.

Hasta pronto

Silvia