Each question contains three statements, one or more of which may not be grammatically correct. You are required to identify the incorrect statements from the options given below and mark that as your answer.
I. The company's profits have risen dramatically over the last fiscal year.
II. She is a diligent worker who complete her tasks on time.
III. His ambition for success have always motivated him to work harder.

Statement I: "The company's profits have risen dramatically over the last fiscal year." This statement is grammatically correct. Statement II: "She is a diligent worker who complete her tasks on time." The correct form should be "who completes her tasks on time." The verb should agree with the singular subject "worker." Statement III: "His ambition for success have always motivated him to work harder." The correct form should be "has always motivated him to work harder." The verb "has" should agree with the singular subject "ambition."