What it is: A bucket-level default that automatically applies a retention mode/period to new object versions (unless explicitly set differently).

What it’s for:

• Enforce consistent baseline retention for new uploads.

Important exam clarifications:

• Bucket default retention sets default mode/period, not a per-object Retain Until Date you manually specify at bucket level.
• Bucket defaults do not “override” an explicit retention you set on an object version in the way the wrong option suggests.

Hard words:

• *baseline* /ˈbeɪslaɪn/: chuẩn nền
• *explicit* /ɪkˈsplɪsɪt/: tường minh (chỉ định rõ)
• *override* /ˌoʊvərˈraɪd/: ghi đè/đè lên