Last reviewed
Correct answer: A. On the web at chatgpt.com and in the iOS and Android mobile apps
Explanation
The principle — ChatGPT is reachable from an ordinary browser and from phone apps, and your account carries your history and settings between them.
Why the key is correct — OpenAI lists the web at chatgpt.com alongside iOS and Android apps, and notes you can even try it without an account in supported regions.
Why the others are wrong — nothing has to be installed, since the browser version needs no download. It is a product you use directly rather than only a component inside other companies' software. And it is not phone-only; the web version is the fullest one.
Remember this — same account, different windows. Signing in is what carries chats and settings across them.
Sources — OpenAI's What is ChatGPT FAQ.
Sources
“Web: chatgpt.com (you can even try it without an account in supported regions). Mobile apps: iOS and Android.”
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