Meaning: 'Differ' means to be unlike or distinct from something else, in this case, referring to the variations in traits among individuals.

Wrong options:

• form: 'Form' is a noun that refers to the shape or structure of something, which does not fit the context of describing how individuals relate to their traits.
• growth: 'Growth' is a noun that refers to the process of increasing in size or development, which does not apply to the concept of variation in traits.
• rough: 'Rough' is an adjective that describes a texture or surface, which is irrelevant in the context of discussing inherited traits.
• evolutionary: 'Evolutionary' is an adjective that describes something related to evolution, but it does not fit as a verb to describe what individuals do with their traits.
• for: 'For' is a preposition that indicates purpose or direction, which does not fit as a verb in this context.

Correct answer: evolutionary

Explanation: The adjective 'evolutionary' describes the type of change that occurs as a result of natural selection acting on inherited traits. It fits grammatically as it modifies the noun 'change' appropriately within the context of Darwin's theory.

Meaning: 'Evolutionary' refers to changes that are related to or resulting from evolution.

Wrong options:

• form: 'Form' is a noun that does not describe a type of change and does not fit grammatically with 'change.'
• growth: 'Growth' is a noun that refers to an increase in size or development, which does not specifically relate to the concept of evolutionary change.
• rough: 'Rough' is an adjective that describes texture and does not apply to the context of change in evolution.
• differ: 'Differ' is a verb and does not fit as an adjective to describe the type of change.
• for: 'For' is a preposition that does not describe a type of change and does not fit grammatically.

Correct answer: evolution

Explanation: The noun 'evolution' refers to the process of change in the heritable characteristics of biological populations over successive generations. It fits grammatically as it serves as the object of the preposition 'for,' indicating what the variation is a prerequisite for.

Meaning: 'Evolution' is the process through which species change over time through natural selection and genetic variation.

Wrong options:

• form: 'Form' is a noun that refers to the shape or structure of something, which does not relate to the process of change in species.
• growth: 'Growth' is a noun that refers to an increase in size or development, which does not accurately describe the process of evolutionary change.
• rough: 'Rough' is an adjective that does not relate to the concept of evolution and does not fit grammatically.
• differ: 'Differ' is a verb that does not serve as a noun to describe the process of change in species.
• for: 'For' is a preposition and does not fit as a noun to describe the process of evolution.

Correct answer: for

Explanation: The preposition 'for' indicates the purpose or reason behind the understanding of genetic differences. It fits grammatically as it connects the action of setting the stage with the intended outcome of understanding.

Meaning: 'For' is used to indicate the purpose or intended goal of an action.

Wrong options:

• form: 'Form' is a noun that does not indicate purpose and does not fit grammatically in this context.
• growth: 'Growth' is a noun that does not convey purpose and does not fit in the context of setting the stage for understanding.
• rough: 'Rough' is an adjective that does not indicate purpose and is irrelevant in this context.
• differ: 'Differ' is a verb that does not fit as a preposition to indicate purpose.
• evolutionary: 'Evolutionary' is an adjective that does not serve as a preposition and does not fit grammatically.