Why Do Researchers Use Random Assignment to Place Participants into One

Why do researchers use random assignment to place participants into one of two or more groups?

A) To eliminate the effect of the independent variable on the dependent variable.
B) To randomly distribute the presence of potentially influential differences between groups and increase the chance of drawing a causal inference.
C) To make sure that groups in a study are as different as possible at the beginning of the study.
D) To correlate the independent and dependent variables.