A camper stands in a valley between two parallel cliff walls. He claps his hands and notices that the echo from the nearby wall returns 0.9 s later while the echo from the farther wall returns 1.10 s later. If the air temperature is -10 C, how wide is the valley?

An example of environmentally learned behavior is aggressive behavior, i grew up seeing many aggressive people in my life and a slowly started picking up those traits however i was able to call myself out and not give in to those traits.

An atom's smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to move. 

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

Iwould think it is temperature, silica, oxides (gases)