Answer:
The last one
Step-by-step explanation:
Class One
1 Class picture: 10 minutes
21 individuals : 21 * 3 = 63
Class Two
1 class picture : 10 minutes
21 individuals : 3 * 21 = 63 minutes.
Totals
2 class pictures = 10 * 2 = 20 minutes
42 individuals : 63*2 = 126
Total 146 minutes
146 minutes / 60 minutes = 146 - 120 = 26
120 minutes = 2 hours
The answer is 2 hours 26 minutes.