In a 200-turn automobile alternator, the magnetic flux in each turn is φb = 2.50 10-4 cos ωt, where φb is in webers, ω is the angular speed of the alternator, and t is in seconds. the alternator is geared to rotate three times for each engine revolution. the engine is running at an angular speed of 1.00 103 rev/min.

(a) determine the induced emf in the alternator as a function of time. (assume is in v.) =
(b) determine the maximum emf in the alternator.

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current