将答案发送到服务器，并从服务器返回相关数组以获取下一个输入选项

I'm trying to get the following to work: I would like to send an answer to a drop-down menu question to a php script, which in turn will give me back a new selection from the database. I then want to use this new selection to change the available input options in a secondary drop-down menuI'm trying to get the following to work: I woul