Time Machine backup takes a long time to complete

Which is a valid troubleshooting step to resolve a customer’s complaint that his Time Machine backup takes a long time to complete?
A. Quit unused applications.
B. Purchase a larger backup drive.
C. Reselect the drive as your backup drive.
D. Use Wi-Fi instead of ethernet when possible.
[toggle title_open=”Close Me” title_closed=”Answer” hide=”yes” border=”yes” style=”default” excerpt_length=”0″ read_more_text=”Read More” read_less_text=”Read Less” include_excerpt_html=”no”]A[/toggle]