Bacteria 1 Count:
5,000/6,000=0.83
4,500/5,000=0.90
4,000/4,500=0.89
3,200/4,000=0.80
The proportion in the count varies (0.83, 0.90, 0.89, 0.80), then the count in the bacteria 1 is not changing exponentially
Bacteria 2 Count:
6,000/8,000=0.75
4,500/6,000=0.75
3,375/4,500=0.75
2,531/3,375=0.75
The proportion in the count is constant (0.75), then the count in the bacteria 2 is changing exponentially
Answer: Second Option: Only the count of bacteria 2 is changing exponentially.