One advantage of random assignment is that it minimizes preexisting differences between the experimental group and the control group.

I think this is a true or false question 
The above statement is true. 
As we can see that there are always some sort of affinity among people some have highly positive towards some and negative towards others so they will try to group up with the ones they like but this would always lead to dissatisfaction of some people in group as they will feel unfair as they are not in group they wanted but in random assignment no one has control so even if they are unsatisfied they cant blame it on others. So there are lesser differences