On the morning of her presentation, Clara finished her final slide. Now, three hours before her presentation, she called a friend to ask what building and room number she will be presenting in. What is Clara's big mistake?

A. Clara didn't remember to save her slides in multiple places.

B. Clara called her friend that morning when she should have been concentrating only on her presentation.

C. She finished her final slide that morning, which means she obviously forgot to run the spelling checker.

D. Clara forgot to inquire about her presentation room, since she does not even know if it has a projector.

[D] seems to be the most viable option. If the room she is presenting in does not have a large screen or projector of any sorts, then she is fairly screwed, due to her presentation being in digital format.

For [A], saving in multiple places isn't necessary, as long as she has it on the one place that she needs it, or even on a removable media, such as a flash drive.

[B] seems like she called her friend after the presentation was completed, not before. Nevertheless, the call was regarding the presentation, and was information that Clara needed to know, so no mistake done here.

[C] is just utterly silly in my opinion. It's not the end of the world if the presentation has some typos. Granted, it would be more professional without them, but forgetting to spellcheck is the least of her worries. Additionally, we can't just use the term "obviously"; never assume anything.

Clara forgot to inquire about her presentation room, since she does not even know if it has a projector.