Detailed Instructions: In this task, you need to provide the correct option for a given problem from the provided options.
Problem:Problem: the duplicate ratio of 1 : 4 is ? 
Options: a ) 1 : 2 , b ) 1 : 4 , c ) 1 : 8 , d ) 1 : 18 , e ) 1 : 13
Solution:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
c