If the tape pulled from the dispenser has a charge of 0.15 μC per centimeter, what length of tape is needed to transfer 2.1 × 10^13 electrons to the remaining tape? Choose the correct option:

A) 0.15 μC per centimeter
B) 2.1 × 10^13 electrons
C) The length of tape is not specified
D) The charge per centimeter is not specified