Topic: Interchange of Parts of Speech,

Best Answer Explained in Below-:

The question asks for the noun form of the verb "imagine." Among the provided options, the word "imagination" is the correct choice.

1. **Definition and Functions**: "Imagine" is a verb that refers to the act of forming mental images or concepts of things not present or not having occurred. The noun form should represent the concept or state related to this action.

2. **Analyzing Options**:
- **A) Imagination**: This noun refers to the faculty or action of imagining, which encompasses the ability to create ideas or concepts in the mind. It directly derives from the verb "imagine" and embodies the essence of the action.
- **B) Imaginary**: This is an adjective describing something that exists only in the imagination.
- **C) Imaginable**: Another adjective, it refers to things that can be conceived or are possible to be imagined.
- **D) Image**: While related, an "image" usually refers to a visual representation and does not capture the broader conceptual aspect of "imagine."

3. **Conclusion**: Given that "imagination" is a direct noun derivative of "imagine," it most accurately fulfills the requirement of the question, highlighting the mental capacity associated with the act of imagining. Thus, the correct answer is A) imagination.