Answer: Fourth option is correct.
Explanation:
Since we have given that
Number of passengers for first car can hold = 6
Number of passengers for second car can hold = 3
According to question, If the ride designer wants to make sure that each run holds at least 12 passengers.
Let the number of 6 passengers cars be 'x'.
Let the number of 3-passengers cars be 'y'.
So, our equation becomes,

Put x = 0, y= 0
So, it becomes 0≥4 which is false.
So, it is shaded away from the origin.
At x= 0, y≥4
at y = 0, x≥6
Hence, Fourth option is correct.