This is the cardinal point of the issue.

The correct answer is: B. vital

A cardinal point is a fundamental or essential principle or feature. In this context, the cardinal point of the issue is the most important or essential aspect of the matter.

Option A, minor, is incorrect because the cardinal point of the issue is not a minor or unimportant detail.

Option C, debatable, is incorrect because the cardinal point of the issue is not something that is open to debate.

Option D, insignificant, is incorrect because the cardinal point of the issue is not something that is unimportant or of little consequence.