.   Which of the following is the best opening sentence for a business letter that you want to sound fairly informal?  

    A. This letter is to make you cognizant of our receipt of your order. 
B. Your order of February 10 arrived in our office today. 
C. Please be advised that I've just received your order. 
D. I am in receipt of your order of February 10.

D?

No. Most people wouldn't say that.

What is the one sentence that most people would say?

I don't think A or C,I'll mostly go with B.

Yes. B is by far the best answer.

Yes, option D would be the best opening sentence for a business letter to sound fairly informal. To determine the best option, you can analyze each of the given options.

Option A: "This letter is to make you cognizant of our receipt of your order." - This sentence uses formal language and may sound too stiff or impersonal in an informal business letter.

Option B: "Your order of February 10 arrived in our office today." - This sentence is clear and direct but lacks a personal touch or friendly tone that you might want in an informal business letter.

Option C: "Please be advised that I've just received your order." - This sentence is also clear and direct but still sounds somewhat formal and lacking personalization.

Option D: "I am in receipt of your order of February 10." - This sentence is personal and uses a more informal tone compared to the other options. It conveys the message straightforwardly while still maintaining a friendly touch.

Therefore, option D would be the best choice if you want to sound fairly informal in a business letter.