Meaning: To 'define' means to state the exact meaning of a word or concept.

Wrong options:

• crime: The noun 'crime' refers to an illegal act, which does not fit the context of defining a robot.
• stay: The verb 'stay' means to remain in a place, which is unrelated to the act of defining something.
• lead: The verb 'lead' means to guide or direct, which does not relate to the context of providing a definition.

Correct answer: call

Explanation: The verb 'call' is correctly used in the present tense to indicate what people do with machines they consider robots. It fits grammatically and contextually as it describes the action of naming or referring to something.

Meaning: To 'call' means to name or refer to someone or something in a particular way.

Wrong options:

• crime: The noun 'crime' does not fit as it does not relate to the action of naming or referring to robots.
• stay: The verb 'stay' does not apply here as it does not convey the action of naming or referring to machines.
• lead: The verb 'lead' does not fit contextually as it implies guiding rather than naming.

Correct answer: comprehensive

Explanation: The adjective 'comprehensive' fits grammatically as it describes the noun 'definition.' It indicates that the definition should be thorough and all-encompassing, which aligns with the context of the sentence discussing the complexity of defining a robot.

Meaning: 'Comprehensive' means including all or nearly all elements or aspects of something.

Wrong options:

• crime: The noun 'crime' does not fit as it does not relate to the concept of a definition.
• define: The verb 'define' cannot describe a noun and does not fit in this context.
• idea: The noun 'idea' does not convey the thoroughness required for a definition.

Correct answer: idea

Explanation: The noun 'idea' fits grammatically as it serves as the object of the preposition 'of.' It is contextually appropriate as it refers to the different perceptions people have regarding what constitutes a robot.

Meaning: An 'idea' is a thought or suggestion about a possible course of action or concept.

Wrong options:

• crime: The noun 'crime' does not fit as it does not relate to personal perceptions or concepts about robots.
• define: The verb 'define' cannot serve as a noun in this context and does not fit grammatically.
• comprehensive: The adjective 'comprehensive' cannot function as a noun and does not fit in this context.