Which of the following is true about diabetes?

think its the second one,have a nice day

The correct answer is b. an operational definition.  

Explanation:

An operational definition constitutes the set of procedures that describe the activities that an observer must carry out to receive sensory impressions, which indicate the existence of a theoretical concept to a greater or lesser degree. In this sense, it tries to clearly indicate how the variables are going to be manipulated or measured and also indicates that to measure a variable, it is necessary to carry out a series of activities or procedures. It is the one that builds or adapts from others, based on the observable characteristics of the phenomenon; indicating the concrete, empirical elements or indicators of the fact to be investigated.