Durgesh is working in a restaurant in which he prepares two types of dishes $A$ and $B$. Dish $A$ takes 20 minutes to be prepared and Dish $B$ takes 30 minutes. He earns Rs 50 to make one packet of dish $A$ and Rs 70 for dish $B$. He works for 12 hours a day, using 1 hour for personal activities. What will be the objective function to maximize his earnings? (Let $x,y$ be packets of $A,B$)

1. A
   $50y+70x$
2. B
   $20y+30x$
3. C
   $50x+70y$
4. D
   $20x+30y$