In electronics, the SI unit for current is Ampere. It is the amount of charge in Coulombs per unit time. It is named after the father of electrodynamics, Andre-Marie Ampere. Also, the current can be easily determined through the Ohm's Law, which states that current is equal to volts divided by the resistance. The answer is letter D.
The moon has phases because as it orbits earth, which causes the portion we see during each different phase to be shown.
40 mi/h means miles per hour