Abicyclist travels at 15 miles per hour south. after 10 minutes, the cyclist is traveling at 20 miles per hour south. which is this an example of? a. acceleration b. speed c. velocity

By adding "south", the speed had both magnitude AND direction, becoming a vector, not a scalar which generic "speed" is. So the second option can be eliminated. Let's analyze the other part(s). A velocity is a distance/time. Do we have that? Yes! -> miles/hour. So, velocity is an option that theoretically fits this question. Buttt... It gives us a time, and acceleration is a change in a velocity (speed, with a direction)/time. So because it says "after 10 minutes", we consider the big picture to be talking about the change in velocity during that time span, which is simplified as "the acceleration" over that time. :)

It is an example of Acceleration.

There was change in velocity within the 10 minutes.

The objects are acted upon by only one force. gravity. mass times the acceleration of gravity (-9.81meters/second squared).

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