What does the $R$ factor account for?

$($a$)$ The resistance of the structural system

$($b$)$ The energy absorption capacity of the structural system

$($c$)$ The stiffness of the structural system

$($d$)$ All of the above

The horizontal dimensions of the lateral force resisting systems for two structures are shown, which building can be defined as a vertical irregular structure?

$($a$)$ I only $($b$)$ II only $($c$)$ I and II $($d$)$ neither

structure I

structure II