Exercise 1: Why Proxy the Lookup Through Express — Possible Solution
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THE THREE REASONS, NONE OF THEM SECRECY
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Since Open Food Facts needs no API key, there's no secret value to protect - so the usual "hide the key from the browser" justification for a server-side proxy doesn't apply here. The chapter instead gives three other reasons:

1. CACHING - the same barcode gets scanned repeatedly over time, and caching the lookup result server-side avoids re-querying Open Food Facts for a product this app has already looked up before.
2. CONSISTENCY - every client (this React app today, a possible future mobile app later) gets identical lookup behavior, since the logic is defined in exactly one place rather than duplicated per client.
3. FUTURE-PROOFING - if Open Food Facts' own API shape changes, or a second data source gets added later, only the server-side code needs to change, not every client that calls it.

WHY THIS WORKS AS AN ANSWER
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It correctly names all three reasons (caching, consistency, future-proofing), and correctly notes that none of them is about hiding a secret, since no API key is involved in this integration at all.