You need a comparison of six suppliers, drawing on their websites and two spreadsheets you hold, with sources you can check. Which ChatGPT feature fits?

The principle — match the tool to the shape of the question, and this one is multi-step, multi-source and needs to be checkable.

Why the key is correct — OpenAI describes deep research as helping you accomplish complex online tasks by reasoning, researching and synthesising information into a documented report, working with uploaded files and searching the public web or specific sites. It proposes a research plan you can review and modify before the work begins, and returns a structured report with citations or source links so you can verify the information. Six suppliers, two spreadsheets and a requirement to check sources is exactly that.

Why the others are wrong — study mode teaches you a subject rather than producing a deliverable. Canvas is where you shape a draft after you have the material, and it gathers nothing. A normal chat can do it, but you supply all the gathering yourself and get no plan to review; OpenAI notes that standard chat may be faster for quick lookups, which is the opposite case.

Remember this — the research plan is the part people skip and should not. Reviewing it before the work starts is cheaper than rejecting the report afterwards.

Sources — OpenAI's Deep research in ChatGPT article.