Process capability index $(C_{pk})$ and Statistical Process Control $($SPC$)$ are both critical tools in quality management. Which of the following is incorrect about the relationship between $C_{pk}$ and SPC$?$

SPC monitors process variation over time to ensure stability.

$C_{pk}$ can indicate whether a stable process is meeting specification limits$.$

$C_{pk}$ measures process capability in relation to specification limits$.$

SPC and $C_{pk}$ are identical, as both only measure process variability.

Both $C_{pk}$ and SPC are used to improve process performance.