Which of the following led to the Trojan War?

I'd go with Paleus and Thetis not inviting Eris to their wedding .

Paris' betrayal of Oenone

Ok.............. after looking at all of these again, I'll go with Aslan on his answer, it is a further reacher answer than Oenone's vengeance against Paris when he left he to kidnap Helen.

On another note, even after Paris abducted Helen, the war might not have occurred if Helen's suitors had not sworn to the Oath of Tyndareus. This oath was extracted from each of Helen's suitors stating that all of them...... regardless of who was chosen as her husband, would swear their allegiance to Helen's chosen husband and defend him against anyone who wished to do him or his marriage any wrong/harm.

I'd say it's a toss up........