Bud,a Parcel Deliveryman,parks His Delivery Truck on a Sloping Road

Bud,a parcel deliveryman,parks his delivery truck on a sloping road.In order to deliver a package,he exits the truck,leaving the motor running.Because he is in a hurry,Bud fails to place the truck's transmission in "park" or set the parking brake.Bud enters a nearby building with the package.Meanwhile,the truck begins to move down the hill.It jumps the curb and strikes two children who are playing in the park.Both children are killed.As to the deaths of the children,the most serious offense Bud has committed is:

A) no offense because the deaths were an accident.
B) capital murder because two children were killed in the same incident.
C) criminally negligent homicide because he was criminally negligent in not following the motor vehicle laws regarding leaving an unattended vehicle running and failing to set the truck brakes.
D) murder because of the "misdemeanor murder rule."