The centering mark should be within ____ of the light field central ray.

You respond to a patient with a report of a mouth infection. Upon arrival, you find a thin man with a prominent fungal infection in his mouth. He denies any history of diabetes mellitus. You should strongly suspect:

A) thrush commonly seen in AIDS patients. B) thrush commonly seen in patients who overdose. C) dentalgia. D) temporomandibular joint disorder.

Upon entering the residence of a man with a supposed heart attack, you find that you have been taken hostage by a young man who has a deer rifle. He orders you to sit down in the corner of the room, where other people have been taken hostage as well. You should:

A) do as your captor orders, try to remain calm, and avoid doing anything to attract attention to yourself. B) follow the orders of your captor, but try to pass by a window in an attempt to attract someone's attention. C) attempt to negotiate with the captor, and tell him that he can keep you hostage if he releases the other people. D) move slowly to your ordered location, wait for the captor to turn his back, and swiftly attempt to subdue and disarm him.