The Question is understood as asking for [the Level of] <em>Education</em> of the respondents in a survey classified as [with values] Institutional, Autodidactic, or Other.
Answer:
The level of measurement is the <em>Nominal Scale</em>.
Step-by-step explanation:
The variable studied here is <em>Education</em> (of the respondents), and it is measured using three <em>categories</em>: Institutional, Autodidactic or Other.
As can be seen, the <em>variable</em> Education is measured using those <em>categories</em> that act as <em>labels</em>. These labels are simply <em>names</em> and they have neither relation in order to the other categories ---that is, no value is higher or lower than other--- and nor numerical meaning at all, as it is with other <em>levels of measurement</em> like Ordinal, Interval or Ratio.
For instance, having an <em>Institutional</em> value is not saying that it represents a higher value than having Autodidactic value or Other value. Moreover, if we substituted Institutional, Audidactic and Other by 0, 1, or 2, these values have no numerical value but are a way to classify the different possible values for the Education variable.
In other words, they represent only a way to <em>classify</em> values for the Education variable. No more than this.
As a result, the level of measurement for the variable Education is the Nominal Scale.