A small company borrows money and remains in debt to its lenders for a period of time. The function f(x)=−6x2+8x+50 represents the amount of debt the company has, in thousands of dollars, x years after opening its business. Approximately how many years after opening its business will the company be out of debt?

A. 2.9
B. 3.2
C. 3.6
D. 4.2