A gender gap is most likely to occur in an election in which the major issue is
To determine which major issue is most likely to result in a gender gap in an election, we can refer to the article you provided from Ms. Magazine. According to the article, the major issue that has consistently shown a gender gap in voting patterns is women's rights.
In order to understand why women's rights might result in a gender gap, we need to consider the political and social dynamics at play. Historically, women have faced inequalities and discrimination in various aspects of their lives, including politics. Therefore, it is likely that women's rights issues, such as equal pay, reproductive rights, and gender-based violence prevention, would be of special importance to women voters.
To find the answer to this question, the most effective strategy is to look for empirical evidence and research studies that examine voting patterns and gender gaps in relation to different major issues. In this case, the article you provided is a reliable source that specifically discusses the gender gap in relation to women's rights.
Therefore, the correct answer to the question is B. women's rights.