Step 1: Understand the business term.
A circular letter is a written communication prepared in one standard format and sent to many people at the same time.
It is commonly used by organizations to inform customers, employees, dealers, or shareholders about important announcements.
Step 2: Understand its purpose.
Circular letters are issued to communicate information such as:
• introduction of new products,
• change in address,
• revision of prices,
• opening of a new branch,
• changes in policies, or
• other important announcements.
Step 3: Analyse the options.
• (A) Incorrect. A confidential message is sent individually, not through a circular letter.
• (B) Correct. A circular letter is specifically intended to communicate the same information to a large number of recipients.
• (C) Incorrect. A demand or reminder letter is used to request payment.
• (D) Incorrect. Complaint replies are written as individual business letters.
Step 4: Final conclusion.
\[
\boxed{\text{Circular Letter}=\text{Communicate information to a large number of people simultaneously}}
\]
Hence, the correct option is \(\boxed{(B)}\).