Rollups can be performed on all the following field types except?

Rollup fields in Microsoft Dataverse are designed to perform calculations over related records and aggregate the results into a single field. These calculations can include summing, counting, and averaging values from related records based on specific criteria.

The function of a rollup field hinges on its ability to operate with numerical and date data types. Currency, whole number, and date fields are all numerical types that can be aggregated logically. For example, you can sum currencies, count whole numbers, or average dates for reporting purposes.

In contrast, text field types do not support rollup functions because text data cannot be logically aggregated in the same manner. Text fields lack a quantitative basis for operations like summation or averaging, which are essential for rollup functionality. This inability to aggregate results makes text fields unsuitable for rollup fields, hence clarifying why this is the exception among the given choices.