Suppose the reaction temperature x (in 8°C) in a certain chemical process has a uniform distribution with a lower limit of 5°C and an upper limit of 25°C. Find all points on the graph of the function f(x)=2sin(x)sin2(x) at which the tangent line is horizontal. (Use n as your arbitrary integer.)

a) x=2nπ​
b) x=nπ
c) x=4nπ​
d) x=0