Answer: a. The women in the background are complementing their verbal communication with their body language.
When we look at the picture, we get a strong feeling that the women in the background are talking about the woman in front, most likely in order to "gossip." The reason why we can understand this without knowing the words they are uttering is because of their body language. The women are leaning towards each other, with their hands over their mouths so they are less likely to be heard. Moreover, the listener appears to be surprised. These are all ways in which the two women complement their verbal communication with their body language.
