If Toyota makes 10 million cars its long run ATC is $\textbackslash$20,000$ car. If it makes 11 million cars its long run ATC is $\textbackslash$25,000$ car. What is the best description? 
选项为:A:economies of scale  B:diseconomies of scale  C:constant returns of scale  D:increasing returns to scale  E:none of the above  请回答其中一个选项.