问题如下：
Which of the following is least likely to be considered an advertisement for the purposes of the GIPS Advertising Guidelines?
选项：
A. A letter addressed to prospective clients.
B. Written material used in one-on-one presentations.
C. A quarterly report e-mailed to multiple existing clients.
解释：
B is correct.
The following definition of "advertisement" is provided in the GIPS Advertising Guidelines: "For the purposes of these guidelines, an advertisement includes any materials that are distributed to or designed for use in newspapers, magazines, firm brochures, letters, media, or any other written or electronic material addressed to more than one prospective client. Any written material, other than one-on-one presentations and individual client reporting, distributed to maintain existing clients or solicit new clients for a firm is considered an advertisement." (See Section 5 of the reading.)
这道题啥意思讲的是什么？