Which explains whether or not the function represents a direct variation? This function represents a direct variation because it passes through the origin and has a constant rate of change of $5 per hour.
This function represents a direct variation because it has a positive, constant rate of change of $10 per hour.
This function does not represent a direct variation because it does not represent the cost for 1 hour.
This function does not represent a direct variation because the function rule for the cost is to add $10, not multiply by a constant.