For a more intimate experience, Google this first and then phrase the question so it invites dialog. An oath taken is the same as a fiduciary dynamic which is a constant high trust given and received. It acts just like the principal would themselves but more so...

Fiduciary duties are like blood, oxygen, food, and water to human life. They are ALL critical if you want to avoid fines, stay in business and out of jail.

Sadie,

Carol Williams said it perfectly.  A

Good luck with your studies sadie moulton , sorry you are starting out with an instructor that makes students ask the same question over and over and over and over and over and over..... If you get some hostile reactions now you know why.

All of them are important if you want to stay out of trouble.

The one you ignore that kisses your license goodbye!

As many have said before in response to this question, they are ALL important!!

Sadie, this is got to be the most asked question by the students on this site so forgive the vague sarcasm but they’re all important how do you determine which truth is the most important truth otherwise?

There is no hierarchy of importance for fiduciary duties.  Would be refreshing to have your instructor bother to come up with some new or more relevant questions that are not asked here hundreds of times each month.

There is no "most important" fiduciary duty.

Acting as a fiduciary means acting honestly, in the best interest of your client at all times. A fiduciary hold the interest of the client above their own interest.

They are ALL important.

I wish you all the best with your real estate studies. 

Jeff Dowler, CRS nailed this one!