The correct answer is A. To return a tabular value for each input row.

A User-Defined Table Function, or UDTF, returns a set of rows instead of a single scalar value. This is different from a scalar UDF, which returns one value for each input row.

Why A is correct:

A UDTF produces tabular output. It can return multiple rows and multiple columns, depending on how the function is defined.

Example concept:

SELECT *

FROM TABLE(my_udtf(input_column));

This syntax shows that the function result is treated like a table.

Why the other options are incorrect:

B. Returning a pandas Series is associated with vectorized Python UDF behavior, not the general definition of a UDTF.

C. Returning one output row as a single column or value describes a scalar UDF, not a table function.

D. Processing input rows as pandas DataFrames is associated with Snowpark Python and vectorized processing patterns, but it is not the basic Snowflake definition of a UDTF.

Official Snowflake documentation reference:

Snowflake documentation defines a UDTF as a user-defined function that returns tabular results. It can return multiple rows for each input row.