I am not sure if my approach is correct. Giving a try.
if the split between $40 and $60 tickets is equal then (40x25)+(60x25)=2500. Avg=2500/50=50.
Now, to keep the avg above 50, number of people with $60 tickets needs to be increased.
New split: 24x40$ and 26x60$= 2520. Avg=2520/50=50.xy>50.0. Since its given that avg is more than 50, so we will solve further using this split, i.e. 24 tickets for 40$ and 26 tickets for $60.
To bring the avg below 50, lets add one to $40 ticket count
Split: 25x40$+26x60$=2560. Avg=2560/51=50.xy>50.00. Hence '1' can definitely not be included.
Adding one more to $40 count
Split: 26x40+ 26x60=2600. Avg=2600/52=50.00. Not less than 50. Hence '2' can definitely not be included.
Adding one more:
Split: 27x40 + 26x60=2640. Avg=2640/53=49.xy<50.00. Hence '3' can be there atleast in one of the possible case.
Therefore, option D is the answer.
It took me some time. A different approach might save some time.