Which phrase would be considered inappropriate for a thesis statement?

A thesis statement serves as the central argument or claim that a writer intends to support throughout a piece of writing. It should be a definitive assertion that provides a clear direction for the paper, guiding both the writer and the reader.

Using a question as a thesis statement is inappropriate because it does not provide a clear stance or argument. Instead of asserting a position or claim that the writer will defend or support with evidence, a question leaves the argument open-ended and vague. A well-crafted thesis should present a statement that can be developed and analyzed, rather than posing an inquiry that invites further questioning without a definitive answer.

In contrast, phrases like "an innovative argument," "a claim based on research," and "a detailed assertive statement" all indicate strong positions or assertions that can be supported with evidence, making them suitable for a thesis statement.