Which of the following items should be sent by certified mail?

Sending a dismissal letter via certified mail is an appropriate choice because it ensures that the recipient receives the document and provides verification of its delivery. Certified mail offers tracking capabilities, which can be crucial in sensitive situations such as employment termination. This method of mailing also provides proof of mailing and delivery, which can be important for legal purposes, especially if there are disputes or claims regarding the employment decision.

In contrast, other options may not require the same level of tracking or verification. For example, lab specimens are typically sent using special courier services that prioritize speed and temperature control, while billing statements are usually sent through standard mail or electronic methods, which suffice for billing and record-keeping purposes. Prescription medications also follow specific regulations for shipping, typically requiring pharmaceutical couriers rather than certified mail. Thus, while certified mail offers a valuable service for important documents, it's particularly fitting for situations where confirmation of receipt is essential, such as in the case of a dismissal letter.