To answer this question, we need to understand the concepts of Work Party rules and Model rules in Pega.
A Work Party rule is used to define the participants or parties involved in a case or process. It allows you to specify the role, type, and other information about the party. The Work Party rule form contains rows for each party involved.
The statement in question states that for a single Valid Party row on a Work Party rule form, the Model column contains an optional field to reference a Model rule. This statement is true.
Model rules in Pega allow you to define default information for specified fields on the PartyDisplay form. By referencing a Model rule in the Model column of a Valid Party row, you can automatically populate the specified fields with the default values defined in the Model rule.
Therefore, the correct answer is A) True.