Which three statements are true about tuning dimensions and details of v$sys_time_model and DB time?

Statspack cannot account for high CPU time when CPU TIME is a Top 10 event in DB time. When CPU time is high, SQL tuning may improve performance.

Systems in which CPU time is dominant need more tuning that those in which WAIT TIME is dominant.

The proportion of WAIT TIME to CPU TIME always increases with increased system load.

When WAIT TIME is high, instance tuning may improve performance.

Parse Time Elapsed accounts for successful soft and hard parse operations only.

DB Time accounts for all time used by background processes and user sessions.