A data engineer ingests semi-structured JSON logs into a Delta table using Auto Loader with...

With schema evolution enabled, Auto Loader detects source fields that are not present in the current schema and evolves the destination schema to include them. The new userAgent field is therefore added to the Delta table as a column, and values from newly processed records are written to it. Existing rows cannot be retroactively populated because the earlier source records did not contain that field, so they receive NULL for the newly added column. The column is consequently nullable unless a later transformation explicitly enforces another constraint. Option A describes behavior without suitable schema evolution. Option B incorrectly claims that historical rows receive a default value and that the column becomes non-nullable. Option D contradicts schema-evolution behavior. Therefore, option C correctly describes how the new JSON field is handled.