A popcorn company would like to determine the optimum microwave settings for popping a bag of its popcorn. They will test two different cooking times (4 minutes and 5 minutes) and three different temperature settings (low, medium and high). Three bags of popcorn will be popped at each combination of factor levels in the same microwave, with the order randomly determined. The number of unpopped kernels will then be compared for each treatment.

What is/are the factor(s) in this experiment?