In this scenario, the rabbit population doubles each month for 8 months. The common ratio in a geometric sequence is the factor by which each term is multiplied to obtain the next term.
Given that the population doubles, the common ratio \( r \) is:
\[ r = 2 \]
So, regardless of the starting population of 16 rabbits, the common ratio remains 2 as the population grows by a factor of 2 each month.