During a demonstration of a Commercial Off-the-Shelf (COTS) software, a comprehensive evaluation is required to ensure it meets the organization's needs. This involves assessing both functional and non-functional requirements. Functionality (C) is paramount to confirm the software can perform the required business tasks. However, non-functional aspects are equally critical for user adoption and long-term success. Understandability (A), Clarity of Communication (B), and the Effectiveness of Help Routines (D) are all key components of usability. A system that is functional but not usable will result in low productivity, user frustration, and increased support costs. Therefore, all listed aspects must be observed for a thorough and effective evaluation.

A. Understandability: Incomplete. Observing only understandability ignores the software's core functions and other critical usability aspects like available support.

B. Clarity of Communication: Incomplete. Focusing solely on communication clarity overlooks whether the software actually performs the required tasks and is easy to learn.

C. Functionality of the Software: Incomplete. While crucial, assessing only functionality neglects usability, which is vital for user adoption and long-term success.

D. Effectiveness of Help Routines: Incomplete. Evaluating only help routines is insufficient; the primary software functions and overall intuitiveness must also be assessed.

1. Paul, D., Yeates, D., & Cadle, J. (2020). Business Analysis (4th ed.). BCS, The Chartered Institute for IT. In Chapter 10, "Making a Business and Financial Case," Section 10.5.2 discusses the evaluation of shortlisted options, emphasizing the need to assess solutions against a range of criteria including both functional fit and non-functional characteristics like usability and support.

2. Sommerville, I. (2016). Software Engineering (10th ed.). Pearson. Chapter 15, "Software Reuse," Section 15.2.2 on "COTS system assessment" explains that the evaluation process involves checking for functionality, assessing performance and usability, and understanding the required support. This confirms the need for a multi-faceted observation.

3. Nielsen, J. (1994). Usability Engineering. Morgan Kaufmann. Chapter 2, "Usability Heuristics," outlines key principles for usability inspection. Principles such as "Help and documentation" (related to Help Routines), "Consistency and standards," and "Aesthetic and minimalist design" (related to Understandability and Clarity) are presented as essential for evaluating a system's user interface.