What are those additional columns?

A stream stores data with the same columns as the source data but with additional columns.

What are those additional columns?
A . METADATA$ACTION
B. METADATA$ISUPDATE
C. METADATA$ROW_ID
D. METADATA$DELETE

Answer: A,B,C

Explanation:

https://docs.snowflake.com/en/user-guide/streams.html#stream-columns Stream Columns

A stream stores data in the same shape as the source table (i.e. the same column names and ordering)

with the following additional columns:

METADATA$ACTION

Indicates the DML operation (INSERT, DELETE) recorded.

METADATA$ISUPDATE

Indicates whether the operation was part of an UPDATE statement. Updates to rows in the source table are represented as a pair of DELETE and INSERT records in the stream with a metadata column METADATA$ISUPDATE values set to TRUE.

Note that streams record the differences between two offsets. If a row is added and then updated in the current offset, the delta change is a new row. The METADATA$ISUPDATE row records a FALSE value. METADATA$ROW_ID

Specifies the unique and immutable ID for the row, which can be used to track changes to specific rows over time.