$[15$pts$]($Exercise $18\mathrm{.}4)$ Consider the execution shown below.

LSN

LOG

$($a$)$ Extend the figure to show prevLSN and undonextLSN values.

$($b$)$ Describe the actions taken to rollback transaction T$2.$

$($c$)$ Show the log after $T2$ is rolled back, including all prevLSN and undonextLSN values in log records.