Homies can one of yalls do this im confused

Which of the following graphs could represent a cubic function?

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?

Hart manufacturing had six-month sales of $80 million, with $20 million of that amount from the internet. it set a goal to increase the percentage of total sales coming from the internet by 4 percent in the next six months. the results were total sales of $85 million. if the company meets its goal exactly, what will the dollar amount of internet sales be?