USA company wants to know my race, what to answer?

As a generic answer: USA (and most other western) companies are forbidden from discriminating on the basis of race, either negatively or positively. However, they can report on the basis of race—e.g. "our workforce is 90% white"—which is what this information is used for.

Typically, the information won't be shown to the hiring manager at all, so you certainly shouldn't lie because you think that will help you get the job. There's also normally a "prefer not to say" option; if there's not, you can always select "Other" and write in either "prefer not to say", or even "unsure" if you'd like something which doesn't make it look like you're dodging the question.

Never lie. It always has a chance to bite you.

Take the perfer not to answer option.

This answer is different than the others in that it stresses that unintended consequence of lying is usually worse than being truthful.

In this situation, being truthful shouldn't have an affect.

Can I say that I am multi-ratial or "hispanic"?

You can lie if you want to.

These questions are not for hiring decision.

What say these rules?

There's no rule that requires you to answer the question, if you would prefer not to answer.

Can I help them to show that they employed yet another multi-ratial guy?

That won't help them in any way.

What if I say, that I need to keep my local laws which forbid asking this on a job interview?

Again, you can lie if you would like to. Most managers I know don't want to hire obvious liars.

How look the rejected answers in these stats, is it worser as being white or not?

No hiring manager cares.

If you want to be hired, either don't answer the question, or answer it honestly.

In order to protect against companies engaging in racially biased recruitment procedures, there needs to be a way to observe the racial diversity of the staff (both currently and going forward), so that the protective measures can target companies with an unhealth racial distribution across its staff.

That, in turn, requires you to know the race of your employees so that you can report on your staff's racial diversity (or lack thereof).

But from the other side of the fence, as the applicant, you are not able to distinguish a racially biased company from one that's merely trying to comply with the protections surrounding racially biased hirings.

I understand your apprehension because of this, but at the same time I have to point out that the reason this question is asked is in no way indicative of whether the company has ill intentions with this information - it could very much be the complete opposite.

Couple of things:

1. If you do a video interview or an in person interview, you cannot hide the color of your skin, (Which is how most people judge race).

2. Your name already gave it away. Names tend to be cultural (which leads them to being racial). If your name is whitey mcwhiteface, I am going to guess that you are white for example... If your name is Jose de Los Angeles, you are probably hispanic...

3. In theory they are not supposed to take your race into consideration when interviewing you. In practice? Racial discrimination occurs in every direction, and is usually hard to prove.

What does this mean?

Fill it out, they use it to report racial employment statistics to the US government (required to by law). If they are going to discriminate against you based on race, they will, regardless of how you answer it. Race is one of those things that is hard to hide.