[rltalker]

You have to frame it in familiar terms for Mensa members:

What conclusions can you draw from the following sentence?

"I would posit that most normal, healthy, high-IQ folks never bother, and there's a selection bias at play."

  a) All Mensa members are unhealthy.

  b) There may exist some normal, healthy, high-IQ folks in Mensa.

  c) All Mensa members have high IQ.

  d) No Mensa member has high IQ.