Final answer:
The dependent variable in the popcorn popping experiment is the number of kernels that are popped. This is measured after testing different brands to see which pops the most.
Step-by-step explanation:
In an experiment to determine which brand of microwave popcorn pops the most kernels, the dependent variable is the factor that you measure or observe. The dependent variable in this case is A. Number of kernels popped. This is because the dependent variable depends on the other conditions set by the experiment, such as which brand of popcorn you are testing. The independent variable, which is what you change on purpose to see the effect on the dependent variable, would be C. The brand of popcorn.