Final answer:
The popular symbol set in addition to the Gane and Sarson symbol set used in structured systems design for data flow diagrams is the Yourdon symbol set. Other options like Zachman, Mantis, and Jira do not represent symbol sets for structured systems design.
Step-by-step explanation:
In addition to the Gane and Sarson symbol set, another popular symbol set is Yourdon. The Yourdon symbol set is used in structured systems design and is known for its association with data flow diagrams (DFDs). DFDs are graphical representations of the flow of data within a system, used by system analysts to model or to document a current or proposed system.
The other options listed, such as Zachman, Mantis, and Jira, are not directly associated with specific symbol sets for structured systems design. Zachman refers to the Zachman Framework for enterprise architecture, while Jira is a project management tool, and Mantis refers to MantisBT, an issue tracker. Therefore, the correct answer is Yourdon, which along with Gane and Sarson, forms the basis of two widely recognized symbol sets for DFDs.