A researcher studying handwashing uses guidelines set by the American Society of Microbiology to determine if handwashing has taken place: use warm or hot running water and soap while washing for 10 to 15 seconds all surfaces, including wrists, palms, backs of hands, and under fingernails. This guideline is considered a. the Hawthorne effect. b. an operational definition. c. a correlation. d. a test.

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.

the farther away the object is from the central star (the sun) it's gravitainal pull on the object is weaker when it is farther

explanation: