Add/Remove or Show/Hide drop down list items

Basically I have 3 drop down lists for security questions. I have java script setup that will spring an alert when the box is changed. I need to开发者_运维知识库 know how to add/remove or show/hide an option. like if the first box selected option 1....remove option one from the other 2 drop downs as possible selections.

$('selector').append($('select options:gt(n)').detach());