Physical Exam

Your A+ is an F-

“Did I pass, doc?”

“You’ll be pleased to know, you’re in perfect health.”

“Sweet! I’ma be an astronaut!”

“Well . . . no.”

“!!! . . . Why not? You said I’m in perfect health!”

“You have type A-positive blood. Astronauts are required to have type O-positive.”

“That seems arbitrary.”

“No; it’s necessary. If someone got hurt, you couldn’t be a blood donor. The body of any O-type person would reject it. O-positive is the largest blood group type, so we picked that. Sorry.”