C. gather together - This is like "interview", you gather potential employees together before hiring one.
— You don't "gather potential employees together", during an interview. You keep them apart.
You sure don't invite the whole town. You do select viable candidates for a job, and yes you can interview them as a group. I understand the JET program in Japan does this. I have never gone through their interview process, but I did do one similar where we were selected based on a private 1 to 1 discussion as well as a 1 to 10 discussion.
D. disregard - This is like "bias", disregarding a potential employee based on race, sex, or possibly beliefs.
— "to be biassed towards" is not "to disregard": to have bias, you must first "regard" them (i.e. take notice of them). Otherwise you wouldn't know what their sex, etc. was.
http://www.google.com/search?hl=en&q=disregard+that+last+comment
E. dissolve - This is like "fire", dissolving them from the company.
— You don't dissolve something "from" something. When you dissolve a partnership, or a marriage, you dissolve the whole. You are then left with separated components.
Yep, the empoyer stays as one part. The ex-employee goes off and finds another job, the second part.
A. leave idle - This is like "reapply". The potential employee is not wishing to work doing another job or with another company. So, instead of applying to other companies, they "idle" until the next time they can apply.
— With "leave idle", the potential employee is the object of the verb. With "idle", the p.e. is the subject. You have switched from one to the other. (You can't leave yourself idle.)
So, is this person going to illegally enter the company's premises and force a job be granted? Are they going to do this through some union?
B. deny access - Well, I think this is like "not employ". You are not forcing/allowing a potential employee to wait, you are simply denying access to your company or the company you represent. These potential employees you deny access can apply to other companies, and assuming they all get jobs elsewhere, they won't be idle. Even if they don't get a job, I don't feel they are in idle as they are doing something to get a job.
— Now you're discussing one possible antonym (deny access) in terms of another (leave idle). Your task is to demonstrate that "deny access" is an antonym of "employ". But in fact you've demonstrated that those who are denied access may in fact get jobs elsewhere. In other words, they may be employed.
They will never be employed by the same company unless there is some reapplication or change in the previous decision to NOT EMPLOY them (which is the best thing to an antonym as I can see). The task is not to demonstrate that "deny access" is the antonym of "employ", the task is to choose the best answer that best fits. That doesn't mean it will correspond 100% to our perception of the antonym of "employ".
In order for the answer to be A, I would think of a person who has lost all hope. They aren't going to apply to another company, and they aren't going to reapply to the same company. They are just going to sit there in idle misery.
— So...umm...that would mean they were unemployed, no?
Yes, but many people don't do that. They look for another job and get employed elsewhere (people got to eat). They don't just sit there idle (and starve to death).