In the past, construction workers who installed steel rods in

the floors of large buildings had been spending most of their work days awkwardly bent over. To avoid injuries and to minimize fatigue, machines were designed that allowed workers to do the job while standing upright. Through testing, it was found that the construction workers were able to use the newer machines faster, and they spent less time in backbreaking positions. Thus, more effective and healthier construction approaches were devised through
a. pragmatic testing.
b. operational acquisition.
c. humanistic assessments.
d. usability testing.

ANSWER: d