One of the key questions (according to Kaplan, and I found it to be true) that you must ask yourself when dissecting NCLEX questions is whether the question gives adequate assessment information or whether more assessment is necessary.
So, even if the question says "intervention", if in order to answer it, you need more data, you would still need to assess. In that sense, as unfair as it may seem, an assessment can for all intents and purposes be an intervention. An answer in which the key verb is "determine" would be an assessment answer, of course.
In other words, don't get stuck on nomenclature, the concepts are often more important than the terminology.