A Point Which Is Outside of the Lower Control Limit

Multiple Choice

A point which is outside of the lower control limit on an R-chart

A) is an indication that no cause of variation is present.
B) should be ignored because it signifies better-than-average quality.
C) should be investigated because an assignable cause of variation might be present.
D) should be ignored unless another point is outside that limit.
E) is impossible since the lower limit is always zero.