The correct option is B for
When a sentence is made up of independent statements, where one statement is a fact provided by or inferred from the other, then an Illative conjunction is used. The statement "her eyes were red and crinkly" is the fact that infers or concludes the other statement "She definitely looked like she had been crying". 'Or' is an alternative conjunction, which presents a choice between two alternatives. As the given sentence requires an Illative conjunction and not an alternative conjunction, option D is incorrect. 'For' is an Illative conjunction, hence option B is correct. 'Although' is a subordinating conjunction, used for contrast-related sentences. As the given sentence is not contrast-related, but inference-related, option A is incorrect. 'But' is an adversative conjunction that expresses a contrast between the clauses in a sentence, since the given sentence does not express a contrast, option C is incorrect.