Final answer:
The correct option is C) Emotional Bias.
The term that best describes a situation where two individuals with personal grudges argue on a subject but are influenced by their emotions towards each other is Emotional Bias. It is not an ad hominem attack, as the personal grudges do not direct the argument's content, but rather its intensity.
Step-by-step explanation:
The term that best describes a situation where two individuals, A and B, have personal grudges but stick to the subject matter during an argument, even though the heat of the argument is based on their personal enmity, is Emotional Bias. This is because, while their argument may be centered on the topic, the intensity and possibly the direction of the argument are influenced by their underlying emotions towards each other.
An ad hominem attack is a logical fallacy where the arguer attacks the person rather than their argument or position. In this case, since A and B's points are focused on the subject, it is not an ad hominem. A reverse ad hominem would imply that the person's attributes are used to support their argument rather than attack it, which is also not applicable here.
Subjective Argumentation would imply that the argument is based on personal opinions rather than facts, which isn't necessarily indicative of personal enmity affecting the tone of the discussion.