Which level of production will maximize profits for a firm producing goods x and y, selling them for 5 and 7 euros respectively? The cost function for the firm is C(x,y) = x² + y² + 10xy - 2x - 4y + 100. What is the optimal production level that will maximize profits?
Options:
A) x² + y² + 10xy - 2x - 4y + 100 = 0
B) x = 0 and y = 0
C) x = 1 and y = 1
D) x = 2 and y = 3