Answer d: BigFieldhas higher process variability than Littlefield labs.
Though Big field and Littelfield has the identical process design and identical process set up with same processing time and capacities to test blodd samples, but the average time taken by the Bigfield lab is higher than the Littlefield lab, this indicates that the vairability is high in the Bigfieldlab. Due to the higher variability of the Bigfield lab, it is taking higher lead time for the blood samples tests.
If the variability is low, then the testing will be completed speedly and it will take low time.