Why Correct: Longitudinal studies track the same individuals over time, allowing direct observation of developmental changes across different ages.
Distractor Analysis: Correlational studies examine relationships between variables without establishing causation. Naturalistic studies observe behavior in real-world settings without manipulation. Cross-sectional studies compare different age groups at a single time point, showing age differences but not developmental change.
Takeaway: Cross-sectional studies are faster and cheaper but cannot distinguish age effects from cohort effects, while longitudinal studies can track individual developmental trajectories but require more time and resources.

Why Correct: Howard Gardner's multiple intelligences theory specifically rejects the concept of a single general intelligence factor (g-factor) that underlies all cognitive abilities.
Distractor Analysis: Social skills correspond to interpersonal intelligence in Gardner's framework. Language skills represent linguistic intelligence. Musical skills constitute musical intelligence, one of Gardner's original eight intelligences.
Takeaway: Gardner's original eight intelligences are linguistic, logical-mathematical, spatial, bodily-kinesthetic, musical, interpersonal, intrapersonal, and naturalistic, with existential intelligence added later as a possible ninth.

Why Correct: Earthworms aerate soil, improve drainage, and decompose organic matter into nutrient-rich castings that enhance soil fertility and crop yields.
Distractor Analysis: Cows provide milk and labor but are livestock, not soil enhancers. Rhizobium is a nitrogen-fixing bacterium that forms root nodules in legumes, not an animal. Honey-bees pollinate crops but primarily benefit horticulture, not general soil health.
Takeaway: Earthworms increase soil porosity by 30-40% and can process up to 36 tons of soil per hectare annually, making them vital for sustainable agriculture.