Which index type suits equality lookups on a JSONB column's keys?

1. A B-tree on the whole column
2. ✓ B GIN with jsonb_path_ops (correct answer)
3. C HNSW
4. D BRIN

Shortcut: GIN indexes the contents of JSONB documents and supports containment operators efficiently. jsonb_path_ops produces a smaller, faster index for the @> operator.