The elbow is considered a third class lever because
a. the effort is applied further from the fulcrum than the load
b. the effort is applied closer to the fulcrum than the load
c. the fulcrum is in the center of the lever
d. the elbow is used to lift objects

The elbow is a type of joint that is considered to be a third class lever. This is because when using the elbow the effort applied is closer to the fulcrum than it is to the load. Because of this, the elbow falls into this sort of classification of levers.

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