The Xavier is most likely to encounter the response bias.
Explanation:
The above scenario is based on the opinion poll in which certain students present their opinions in front of the class. We cannot totally trust this opinion poll since it can be different from the reality. People can tell and act differently.
So the opinion poll method comes under the response bias in which the answers given by the students differ from reality. Respondents may answer differently under the social pressure but later they can do whatever they want.