Please explain to me why the correct answer is C. I kind of get the concept but I don't understand the e math behind it.Thanks

A windshield wiper circuit is designed to use an RC charging circuit as a timer: whenever the capacitor reaches 50% full, the wiper blades are triggered, the capacitor is emptied, and the cycle repeats. Which of the following circuits would correspond to the fastest windshield wipers (that is, the most "wipes" per minute)? Vleilesents time scale A. A circuit with a 10-ohm resistor and a 150 mF capacitor B. A circuit with a 20-ohm resistor and a 100 mF capacitor of charging / ais (yal9ing C. A circuit with a 8-ohm resistor and a 75 mF capacitor Smalles+ 7= smallest D. A circuit with a 20-ohm resistor and a 75 mF capacitor Cus/?( Jim E. A circuit with a 5-ohm resistor and a 350 mF capacitor D= RC