'कैटल' (Cattell) के अनुसार, 'तरल बुद्धि' (fluid intelligence) और 'ठोस बुद्धि' (crystallized intelligence) में अंतर है:

उत्तर: (B) Fluid = reasoning with novel problems; Crystallized = accumulated knowledge and skills — Fluid intelligence (Gf): reasoning, problem-solving with new situations, pattern recognition. Peaks in young adulthood, declines with age. Crystallized intelligence (Gc): knowledge, vocabulary, learne...