A.I. Explanation:

Option 1: "is rest"

Explanation: The text emphasizes the importance of rest and relaxation for managers dealing with stress. It states that managers need to find time for themselves and engage in activities that help them unwind, which directly supports the idea that 'rest' is essential for managing stress effectively.

Option 2: "is a waste of time"

Explanation: This option contradicts the main idea of the text, which highlights the necessity of rest for managers. The text suggests that rest is crucial for managing stress, making this option incorrect as it presents a negative view of rest that is not supported by the text.

Option 3: "is stress"

Explanation: While the text discusses stress as a significant factor affecting managers, it does not suggest that stress itself is a solution. Instead, it emphasizes the need for rest to combat stress, making this option incorrect as it misrepresents the relationship between stress and the required action.

Option 4: "is capacity"

Explanation: This option is incorrect because the text does not focus on 'capacity' as a solution to the issues faced by managers. Instead, it discusses how stress inhibits their capacity to lead, but does not imply that 'capacity' itself is a remedy, thus making this option irrelevant.