The bar across the top of an Office Online program that allows users to find the commands to complete a task is called the

C: Ribbon

Explanation:

These are options for the question

A: Button

B: Clipboard

C: Ribbon

D: Task list

Ribbon as existed as far as late 1980s and can be described as a control element that control several tabs that user is working with, and give room for user to locate the appropriate Command for his/her task execution.

these tabs could be a contextual tabs or other, The application of Ribbon can be found in Word processor.

It should be noted that the bar across the top of an Office Online program that allows users to find the commands to complete a task is called the Ribbon

i think the answer is a, hope this is right, that would be my best guess.