A. Bias by placement, because bias by labeling would be something to the effect of calling the liberals point of view uneducated, or giving there view some negative label, bias by omission would mean completely ignoring the other side, and not covering it at all, whereas all the other ones don't really fit, bias by placement is something to the effect of airing one side in the morning, while everyone is watching, and airing the other one after everyone is asleep, which is what is done here, which we know by the sentence "liberal point of view at the end."