Meaning: Eminent means 'famous and respected within a particular sphere or profession,' indicating that Clark Hull is a well-regarded psychologist.

Wrong options:

• radical: Radical implies a fundamental change or departure from tradition, which does not fit the context of describing Hull's status in psychology.
• elementary: Elementary suggests something basic or simple, which does not convey the level of recognition intended in this context.
• ideal: Ideal refers to a standard of perfection, which does not accurately describe Hull's professional standing.

Correct answer: novel

Explanation: The word 'novel' is appropriate as it indicates a new or unique way of combining behavior segments, which aligns with the innovative aspect of Hull's claim about reasoning.

Meaning: Novel means 'new and original,' suggesting that the way of combining behavior segments is unprecedented.

Wrong options:

• broad: Broad suggests a wide scope, which does not specifically convey the uniqueness required in this context.
• stingy: Stingy implies a lack of generosity, which is irrelevant and does not fit the context of combining behavior segments.
• ordinary: Ordinary means common or unremarkable, which contradicts the idea of a unique approach to reasoning.

Correct answer: goal

Explanation: The word 'goal' fits grammatically and contextually as it refers to the desired outcome of the reasoning process described by Hull, making it a logical choice.

Meaning: Goal means 'the object of a person's ambition or effort; an aim or desired result,' indicating what the reasoning process aims to achieve.

Wrong options:

• category: Category refers to a class or division, which does not align with the intended meaning of an outcome in this context.
• description: Description implies detailing or explaining something, which does not fit the context of achieving an outcome.
• rate: Rate refers to a measure or quantity, which does not correspond to the intended meaning of a target or aim.

Correct answer: explicitly

Explanation: The word 'explicitly' is suitable as it indicates that the test was clearly and directly based on Hull's principles, which is essential for understanding the test's foundation.

Meaning: Explicitly means 'in a clear and detailed manner,' emphasizing that the principles were directly applied in the test.

Wrong options:

• collectively: Collectively implies a group effort, which does not accurately describe the individual basis of the test on Hull's principles.
• approximately: Approximately suggests a lack of precision, which contradicts the clear application of Hull's principles in the test.
• randomly: Randomly implies a lack of order or purpose, which does not fit the context of a structured test based on specific principles.

Correct answer: task

Explanation: The word 'task' fits grammatically and contextually as it refers to the specific activity the children were required to complete, aligning with the overall structure of the sentence.

Meaning: Task means 'a piece of work to be done or undertaken,' indicating the activity the children needed to learn to operate the machine.

Wrong options:

• multiplication: Multiplication refers to a mathematical operation, which does not fit the context of learning to operate a machine.
• area: Area refers to a measure of space, which is unrelated to the activity of operating a machine.
• volume: Volume refers to the amount of space an object occupies, which does not pertain to the task of learning to operate a machine.