Which Statement Best Summarizes the Results of Lisa Freund's Studies

Which statement best summarizes the results of Lisa Freund's studies of children's performance on a sorting task when they were allowed to practise with and without their mothers' assistance?

A) Children who practised the task with their mothers showed decreased performance at test under all conditions.
B) Children who practised with their mothers showed increased performance at test under all conditions.
C) Regardless of whether they practised the task with their mothers, children whose mothers were not present at test showed increased performance due to decreased maternal interference.
D) Regardless of whether they practised the task with their mothers, children whose mothers were present at test showed decreased performance due to increased maternal interference.