A package delivery company wants to satisfy customer expectations of on$-$time delivery. An analyst used DMAIC divergent and convergent procedures to uncover potential causes. The analyst determined the possible vital causes of poor performance are reliability of delivery vehicles, number of deliveries per driver, and traffic. In analyzing the effect of vehicle reliability, the analyst runs a regression analysis and found an F less than $0\mathrm{.}05$ and R$2$ equal to $0\mathrm{.}9210.$ Which action should the analyst take based on those results?

a$.$ Consider moving vehicle reliability issues to DMAIC$$s Improve phase as a key factor.

b$.$ Consider advancing the number of deliveries and traffic issues to DMAIC$$s Improve phase as key factors.

c$.$ Run additional regression models because the results show vehicle reliability is unimportant.

d$.$ Discard the model because of poor regression outcomes.