1. The problem asks to identify the measurement scales for four variables collected from 150 students: Age in years, Grade level, Gender, and Number of hours studying per week. 2. Let's analyze each variable: - Age in years: This is a quantitative variable with a true zero point (age 0 means no age), and differences and ratios are meaningful. This corresponds to a Ratio scale. - Grade level (Freshman, Sophomore, Junior, Senior): These categories have a meaningful order but no fixed interval between them. This corresponds to an Ordinal scale. - Gender: This is a categorical variable with no inherent order. This corresponds to a Nominal scale. - Number of hours studying per week: This is a quantitative variable with a true zero point (0 hours means no studying), and differences and ratios are meaningful. This corresponds to a Ratio scale. 3. Matching these to the options given: - Age in years: Ratio - Grade level: Ordinal - Gender: Nominal - Number of hours studying per week: Ratio 4. Therefore, the correct answer is option (a): Ratio, Ordinal, Nominal, Ratio.