When Ross and Braband (1973) Used a Blind Confederate in an Experiment

When Ross and Braband (1973) used a blind confederate in an experiment in which the confederate and the subject worked in a room into which smoke was introduced:

A) when the smoke was odourless, the subject responded just as quickly on average as did participants in a control condition working alone
B) when the smoke was accompanied by a scream from outside the room, the participants were inhibited to the same extent as were participants working with a sighted confederate
C) there was no bystander effect because the participants were not concerned about acting inappropriately because the blind man could not see them
D) both a and c
E) both a and b