Answer: C. 12,720
Explanation:
In Logistic growth, the change in population is given by :
...(*)
, where P= Initial population , t= time , r= intrinsic rate and
=Change in population and C = Carrying capacity.
As per given , we have
P=12,000
r=0.15
C=20,000
t=1 year
Substitute all values in (*) , we get

Now, Total population of snails after a year =

Hence, the correct answer is C. 12,720 .