Final answer:
Kira should use the Accessibility option under the Help tab in Word Online to find shortcuts for her screen reader, as it provides targeted assistance for users with disabilities.
Step-by-step explanation:
The best way for Kira to find shortcuts for her screen reader in Word Online is to navigate to the Accessibility option under the Help tab. This section is specifically designed to assist users with disabilities by providing information on accessibility features and shortcuts that can be used with adaptive technologies. Since Kira is using a screen reader, the Accessibility option will likely have the most pertinent information to help her with her writing assignments in an efficient manner.