The REFramework (Robotic Enterprise Framework) in UiPath is designed to work with transactional data. For a process that involves iterating over a DataTable where each row represents a transaction item, the appropriate variable type for the TransactionItem would be a DataRow.

In the context of REFramework, a DataRow is typically used to represent a single transaction item when the transaction data is contained within a DataTable. This allows the framework to process each row (or transaction) one by one.

Therefore, the correct variable type for the TransactionItem from the drop-down list should be DataRow.