Survey: Which job would be more frightening an undertaker or a police officer?

Undertaker would be more frightening.

As far as the stress level, I'm presuming that a police officer would have a more uncertain future due to the unpredictability of suspects and/or those committing crime.  The police officer may also need to view a deceased victim or suspect in the course of his or her career.  

An undertaker, mortician or funeral director may find certain aspects of the nature of their work to be disturbing or frightening, though please also be aware that the undertaker usually also needs to be strong in science-related classes, in addition to utilizing counseling methods for grieving families.

This website has more general career info:

https://www.bls.gov/ooh/ and can search "funeral service workers," "police and detectives," or whichever other career that piques one's interest.

Fire fighter. You run into a building on fire to rescue someone and hope you both can get out alive

The job of a police officer.   Dead people usually don't retaliate the way criminals do.  You can reasonably expect a dead person to remain motionless (minus an occasional twitching), but when chasing after thugs, pulling someone over for speeding, or dealing with a domestic dispute, you never know what you might encounter.

An undertaker, because everyone is just dead dead dead