For both physical and psychological measurement, the lowest scale of measurement involves categorizing the stimulus into one of a number of discrete categories (e. g., whether or not someone makes eye contact). This level of measurement is called:

Nominal scale

Explanation:

It is necessary for researchers to quantify responses in a meaningful way.

For example, the level of discomfort a person is feeling can be represented by a scale

1: Mild

2: Moderate

3: Severe

Statistical methods can be applied to the set of responses from different people. The conclusion of their hypothesis can be reached through this process.

Hence, the question is referring to nominal scale.

explanation: