Crikey, you lot don't half complicate things on here. I'll make it simple for you - The Pilot.
The only time the backseater ever dropped a bomb was when the aircraft was in a reversionary mode. And that generally only happened in bombing competitions for sh*ts and giggles.
As a general rule the Nav, WSO, RIO, call him/her what you will, finds the target. The Pilot, stick-monkey, driver, gimp, call him/her what you will, fires/releases the weapon.