To determine the most suitable word to fill in the blank, we need to consider the context of the sentence: "The company's _________ commitment to sustainability is admirable."

The word in the blank should describe the type of commitment a company has towards sustainability. Let's analyze the options:

• resolute: This word means determined or unwavering. While it may seem suitable, it does not directly imply strength in the context of a commitment.
• strong: This adjective denotes firmness, robustness, and vigor, making it a perfect fit to describe a commendable commitment.
• shakeable: This word suggests something that is unstable or can be easily affected, which is contrary to "admirable."
• wavering: This implies inconsistency or doubt, which, like "shakeable," is not aligned with the idea of an admirable commitment.

Therefore, the option that best fills the blank to express an admirable commitment is strong.