Some Psychologists Studied the Bullying Behaviour by Elementary School-Aged Children

Some psychologists studied the bullying behaviour by elementary school-aged children as it occurred during school recess. They found that:

A) the schoolmates were frequently present during bullying episodes but rarely intervened.
B) naturalistic observation was not an effective research method for studying children's bullying behaviour.
C) the research methods did not influence the children's behaviours.
D) the observations made during the research permitted causal conclusions about bullying behaviour.