What is most important for reducing the likelihood of extraneous variables

A)  experimental methods 
B)  correlational methods 
C)  random assignment 
D)  random sampling

Random assignment to conditions helps to reduce the likelihood of extraneous variables because it ensures that participants are distributed across conditions in a way that is not systematically related to any other variables. This helps to eliminate the possibility that any pre-existing differences between participants might account for the differences observed between groups. Experimental methods and correlational methods can both be used in research; however, only experimental methods allow us to make causal inferences about the relationship between variables, which is important for reducing the likelihood of extraneous variables. Random sampling is important for ensuring that our sample is representative of the population of interest, but it does not directly address the issue of extraneous variables in the same way that random assignment does.