Use the Hertzsprung-russel diagram to determine which condition describes each star. Use the arrows to help you locate the stars. Procyon B Polaris
Vega
It is fusing hydrogen at its core.
It has lost its outer shell and retained only a hot core that is slowly losing its
brightness
Its temperature has decreased, but it is shining brighter than before.

The duration of a photographic flash is related to an rc time constantly

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