According to the passage, a thermal carafe is necessary when the coffee is ______.

A．know that someone in authority will reach down and give them a promotion
B．don't want people to think that their promotions were due to sex or color
C．don't want to give people the impression that they work under false beliefs
D．believe they can get promoted by reason of their sex or color

A．as
B．when
C．so that
D．now that