I'm not the best at math, but I tried.
x= the amount of months passed
The question asks for the population of fleas in 1 year, and 1 year = 12 months, then x would equal 12 months
Therefore, you substitute that x with 12
f(x)=250(2^x)-------f(x)=250(2^12)
Now you can solve that part of the problem:
2 to the power of 12= 4096
f(x)=250(4096)
now multiply that:
250×4096= 1024000
The answer is C. 1024000