Final answer:
Option (1), Robert would most likely use his fluid intelligence to solve a complex math problem, as it involves reasoning and handling abstract concepts distinct from recalling learned knowledge.
Step-by-step explanation:
Based on the definition of fluid intelligence by Raymond Cattell, which is the ability to see complex relationships and solve problems, Robert's task that would most utilize his fluid intelligence is solving a complex math problem. Unlike crystallized intelligence, which involves acquired knowledge like recalling historical facts, fluid intelligence is tapped when addressing new problems and unfamiliar challenges.
Solving a complex math problem requires Robert to apply reasoning skills, manipulate abstract concepts, and find solutions, all characteristic of fluid intelligence.