The correct answers are The printer, jammed with a half-eaten sandwich, finally caught fire. and Anyone caught microwaving fish in the breakroom will face immediate suspension.

Participle clauses can be used to reduce relative clauses.

"...jammed with a half-eaten sandwich" is a correct past participle clause replacing "which was jammed...".

"...caught microwaving fish" is a correct past participle clause replacing "who is caught...".

"Left on the desk overnight..." is a dangling participle because it implies Bob was left on the desk, not the sandwich.

"The sandwich eating..." is incorrect because it uses an active present participle (-ing) instead of the required passive past participle (-ed). It should be "The sandwich eaten by the intern...".