since a cell phone is not part of the three, i'll make mine
Multitool
Light
Lighter

this is EDC, not survival oriented. if we're talking survival gear then a three item limit seems a bit silly, but i guess i'd go with the B*** G***** set up of fixed-blade knife, steel canteen cup, and firesteel. with a basic knowledge base, that covers the three essentials of fire(which by proxy also covers illumination and signaling), water, and shelter.