Who among the following is exempt from the architectural practice act as long as they do not use the title architect?

The correct choice is a structural engineer. Under the California Architectural Practice Act, certain professionals are exempt from the restrictions of using the title "architect" as long as they are practicing within the scope of their own licensing and expertise. A structural engineer, for instance, is licensed to perform engineering services that focus on the structural integrity of buildings and may engage in activities regarding the design of structures without being classified as an architect.

While interior designers, construction managers, and project estimators play crucial roles in the building process, their work typically does not encompass the architectural services defined under the act, which often includes the design and planning of buildings as a whole. Therefore, these professionals are likely required to follow different regulations or licensing requirements related to their specific activities, whereas a structural engineer can operate within their field without needing to hold an architectural license or use the architect title, provided they remain within their professional boundaries.