Which statement is true about the Log Writer process? 

Answer options:

A. It writes when it receives a signal from the checkpoint process (CKPT).
B. It writes concurrently to all members of multiplexed redo log groups.
C. It writes after the Database Writer process writes dirty buffers to disk.
D. It writes when a user commits a transaction.

D

References: http://docs.oracle.com/cd/B19306_01/server.102/b14220/process.htm (see log writer process (LGWR))