Thinking of taking AP history next year.. what are your thoughts on whoever that took AP history

Technician a says the harmonic balancer may be attached to the crankshaft using a woodruff key and center bolt. technician b says the harmonic balancer may be attached to the crankshaft using a square key and center bolt. who is correct? choose one answer. a. technician a b. technician b c. both technician a and technician b d. neither technician a nor technician b