Which type of template can a developer select when creating a new SAP Fiori app?

The correct choice for the type of template a developer can select when creating a new SAP Fiori app is the factsheet template. This template is specifically designed to provide a comprehensive view of a particular business object, allowing users to access and interact with relevant data in a user-friendly manner. Factsheets often include contextual information and navigate to various related transactions or data views directly, enabling users to make informed decisions based on rich, contextual information.

The factsheet template helps in creating applications that focus on displaying business information and relevant metrics while allowing users to drill down into details as needed. This aligns well with the principle of Fiori design, which emphasizes simplicity and usability, providing essential information right at the user's fingertips.

In contrast, while analytical and transactional templates are also part of the SAP Fiori design guidelines, the analytical template is focused on presenting visualizations and KPIs to support data-driven decision-making, whereas the transactional template is used for applications that involve task execution, such as creating or modifying records. Web Dynpro is not a template used in Fiori app development; rather, it refers to SAP's technology for building web applications. Thus, the factsheet template stands out as the right answer for the context of the question.