A smartphone device has a certain cost. A person gets this smartphone and signs up for a monthly wireless plan with a fixed base price plus a charge per GB of data used. Which is the Independent Variable in this scenario? A. The cost of the smartphone device. B. The charge per GB of data used. C. The number of GB data used. D. The total amount they pay for the new device and new phone plan in the first month. Need an answer fast! Due very soon! Don't understand!