singular or plural? what concern(s)

A) What concerns me is two facts.

B) What concern me are two facts.

Which one is correct?   

(I find there exists a paradox. A can be correct, because the predicate accords not to the object, but to the subject, whose morph seems singular. B can also be correct, because what can be substituted with "things which", thus the subject is plural.  What do you think?

Thanks in advance!

I googled "what concern me" site:www.nytimes.com  and found this:

These people  - their footprints, actually - are what concern me now. I said they follow the trail, and strictly speaking this is true. ...

Any more comments?

What sometimes seems to have a plural force but nevertheless requires a singular verb. Clearly we would say What is needed is a spotlight, but what if spotlights - the plural form - is used.instead.

The options are these:

    What is needed here is spotlights.

?  What are needed are spotlights.

X  What is needed are spotlights.

The first construction, with both verbs in the singular, is the best by far.

(The Right Word at the Right Time)

Thank you YL, MH, and GG! Your comments are all very helpful indeed!

Kooyeen,

In the parallel pattern, “what bothers me the most…”, or “what kills me the most…, is frequently treated as a singular scenario. “what concerns me is …” should be treated likewise. What follows could be singular or plural which should be separate from this structure. Since “what” is unknown, it should be treated as singular, such as ^{“ who is coming for dinner?” or “who is the father of this child?”.}