For centuries, the two standard forms of written business communication were memos and:

A. e-mails.

B. faxes.

C. text messages.

D. letters.

I'll be glad to check YOUR answer.

D. Letters

The answer to this question is letter D. letters.

To arrive at this answer, it is important to have some background knowledge. The question is asking about the two standard forms of written business communication for centuries. This implies that the answer should relate to traditional methods of communication.

To answer the question accurately, consider the following options:

A. Emails: While emails have become a common form of business communication today, they were not in existence for centuries. Therefore, option A can be eliminated.

B. Faxes: Faxes have been widely used in business communication for several decades. However, they were not around for centuries. Therefore, option B can also be eliminated.

C. Text messages: Text messages are a relatively recent form of communication that became popular with the rise of mobile phones. They have not been in use for centuries, so option C can be eliminated.

D. Letters: Letters have been a standard form of written communication for centuries. They were commonly used in business settings to convey formal messages before the advent of modern technology. Given the historical context, option D is the most appropriate choice.

Therefore, the correct answer is D. letters.