TB MC Qu$.10-68$ A plot below the lower control limit on the $...$

A plot below the lower control limit on the range chart

$($I$)$ should be ignored since lower variation is desirable.

$($II$)$ may be an indication that process variation has decreased.

$($III$)$ should be investigated for assignable cause.

Multiple Choice

II and III

I, II$,$ and III

II only