When dealing with a complex product, what is best defined as a secondary persona?

In persona-based design, a primary persona represents the main target user whose experience is the central focus of the design. A secondary persona represents another user type whose needs are also important to consider. However, the key distinction is that any features or design choices made to accommodate the secondary persona must not compromise or detract from the experience of the primary persona. Their needs are met as long as it doesn't harm the primary user's journey.

B. Someone the product is explicitly not going to satisfy: This defines a negative persona, which is used to clarify who the product is not for.
C. The consumer whose experience is essential...acceptable to alter the product experience of the primary persona: This describes a co-primary persona, not a secondary one.
D. A persona that must be satisfied for the product such that the goals should drive the design process: This is the definition of a primary persona.

1. Scaled Agile, Inc. (2023). Design Thinking. Scaled Agile Framework. Retrieved from https://www.scaledagileframework.com/design-thinking/. (This article discusses the use of personas to understand users, a core concept of which is differentiating between primary and secondary user needs.)

2. Cooper, A., Reimann, R., Cronin, D., & Noessel, C. (2014). About Face: The Essentials of Interaction Design (4th ed.). Wiley. (Chapter 5, "Modeling Users: Personas and Goals," is the seminal work defining primary, secondary, and other persona types, establishing the principle that secondary persona needs should not compromise the primary.)