If the demand for skateboards decreases, you can expect the price of skateboards to increase triple not change decrease

Demand of skateboard decreases it means, most of the people in that location have skateboard or it is replaced by that item which is more worthy and having reasonable price and more efficient than that skateboard.

Being a citizen of earth  he or she will keep in mind that it uses minimum amount of plastic and if that product is made up of plastic it is biodegradable plastic.

So, if this is the case , then price of the skateboard will decrease.

Option D: Decrease

step-by-step explanation:

-6 is the correct option from the above given options