How are window functions different from regular aggregate functions?

A.
Rows retain their separate identities and the window function can access more than the current row.

B.
Rows are grouped into an output row and the window function can access more than the current row.

C.
Rows retain their separate identities and the window function can only access the current row.

D.
Rows are grouped into an output row and the window function can only access the current row.