In order to make a ramp that is 3ft high and covers4ft of ground how long must the ramp be

This seems like a right angle triangle situation
the height is 3ft
the base is 4ft
so we're looking for the hypothenus
so we can use the Pythagoras Theorem
which is
the square of the hypothenus is equal to the sum of the square of the two other sides
hyp^2 is equal to opp^2+ adj^2
hyp^2 equals to 3^2 + 4^2
9+16
25
hyp^2 equals to 25

equals to 5
the ramp has to be 5ft long

B) raising the temperature and reducing the volume of the gas.|-/ 

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