Which Is NOT a True Statement About Challenges for Cause

Which is NOT a true statement about challenges for cause today?

A) A 2011 study found that when a reflective challenge is used, blacks and whites were judged equally by jurors.
B) Banning other prospective jurors from being present during challenges is required in all Canadian courts.
C) Potential jurors are less likely to admit potential bias if others from the panel are present.
D) Currently, Canadian courts use a single, closed-ended question for the cause challenge.