I was able to find two options online for this question. There might be more options, but the correct one was already found, so others are not so relevant. The options I've found are:
a) People are less likely to come to negative assumptions about why a middle-class female needs help.
b) People are always more likely to help someone from the middle-class rather than a lower class.
Answer:
The reason why the researcher felt the female's appearance was important is:
a) People are less likely to come to negative assumptions about why a middle-class female needs help.
Step-by-step explanation:
The fact that we judge people by their appearance is an unfortunate truth. In this experiment, the researcher realized people tended to help a woman in need if she looked "middle-class". That is because people in general tend to make assumptions as to why a person needs help. A middle-class woman is less likely to be judged negatively in that sense. People probably think she is not the cause of her own distress.