A researcher wanted to study the effects of a certain chemical on cel growth. The chemical was to be applied at two different dowsed, high and low, to two different types cell types, strain A and strain B. Each combination of dose and cell type was to be replicated ten times. To have a consistency from one replicate to the next, the researcher decided to use four lab technicians. One technician would be assigned the high dose with strain A. A second would be assigned the low dose with the strain A. The third would be assigned the high dose with strain B. A fourth would be assigned the low dose with Strain B. The assignment of lab technician to the replicates for a combination of dose and cell type would be randomized. A statistician told the researcher that the design could be improved by controlling confounding variables. Which of the following is potentially a confounding variable in this study? A. Chemical used
B. Lab Technician
C. Dose
D. Cell type
E. Cell growth