Suppose that a car dealer had an inventory of $150$ cars on December $31,2015,$ got $35$ new cars shipped from the factory during $2016,$ and sold $20$ cars to consumers during the year, making the dealer's inventory equal to $165$ cars on December $31,2016.$ What was the contribution of the car dealer to inventory investment for $2016?$

Group of answer choices

$165$ cars

$35$ cars

$15$ cars

None of these