The correct answer is A. Time Block .

In Workday Time Tracking, a Sum Related Instances calculated field is used when you want to total values from a set of related records. In this scenario, the goal is to add up the hours worked in a week for entries that use a particular time entry code . Although the overall calculation context may be weekly, the actual hours being summed come from the individual time records , which are stored as Time Blocks .

That is why the related business object for the Sum Related Instances calculation is Time Block . Each time block contains the detailed reported time information, including hours, time entry code, and other attributes used for filtering and summing. The weekly total is produced by summing the qualifying Time Block records associated with the week.

The other options are not correct as the related object for the sum itself. Time Entry Code is a filter attribute, not the object containing the hours to total. Time Week is the broader context or parent level for the calculation, but it is not the related instance being summed. Time Calculation Tag is also an identifying or filtering element used in calculations, not the transactional object that stores the hour values.

So, for a Sum Related Instances field totaling weekly hours by a specific entry code, the related business object is Time Block .