In the following question, out of the four alternatives, select the alternative which is the best substitute for the given words/sentence.
Angry or bitter disagreement over fundamental issues

Let's analyze the given options:
Strife: Angry or bitter disagreement over fundamental issues; conflict.

Accord: An official agreement or treaty (Antonym).

Amity: Friendly relations (Antonym).

Affinity: A natural liking or sympathy for someone or something.

Therefore, Strife is the perfect fit.