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7) Near-sightedness typically develops during the childhood years. Recent studies have investigated a possible association between near-sightedness and the use of night-lights with infants. In a study by Quinn, Shin, Maguire, and Stone (1999), researchers surveyed parents of 479 children visiting a pediatric ophthalmology clinic. One of the questions was "Under which lighting condition did/does your child sleep at night?" before the age of 2 years. The parents chose between "room lighting," "a night light," and "darkness." Based on the child's most recent eye examination, researchers separated the children into three groups: near-sighted, normal refraction, or far-sighted. a. Who are the individuals of interest in this study? b. What is the explanatory variable in this study? Is it quantitative or categorical? C. What is the response variable in this study? Is it quantitative or categorical? d. Is this an observational study or an experiment? How can you tell