Answer: a) is an example of stereotype threat
Explanation:
A stereotype threat is when people might conform to stereotypes about their social groups (in this case, the social group of "older people").
Conforming to this stereotype can be risky, because it might cause certain social groups to "underperform", to perform less than their actual potential. It's good that Mrs. Nguyen has formed her own opinion about getting older and she hasn't submitted to the general perception of about "getting older".
