Final answer:
The statement that uses ethos to argue for more workplace creativity is the one where personal experience about the lack of innovation and its impact on motivation is shared.
Step-by-step explanation:
The statement that relies primarily on ethos to reinforce the argument that workplaces should promote more creativity in their employees is: "My workplace, like that of many office workers, seems devoid of the spirit of innovation and creativity, and my motivation suffers as a result." This statement uses the credibility and experience of the speaker to make a case for more creativity in the workplace, which is the essence of ethos as a rhetorical device. It demonstrates a personal testimony and credibility, suggesting that a lack of creativity at work affects the speaker's motivation, which may resonate with others' experiences.