Which of these birds had the largest wingspan of any flying bird yet discovered?

Ladybug, the question says 'had', so it cannot be any of the other birds listed as they still exist.

am surprised that there hasn't been a program on it, with David Attenborough! coz I know he likes birds. love you Sir David xxx

If it’s extinct, it shouldn’t be the correct answer

Cait, I agree. In earlier times, scientists believe the oxygen content of the air was much higher, allowing a huge bird to fly.

Barbaloola, this bird is extinct, the albatross is extant, so still in existence, and has the greatest wing span now

All the info I have has the wandering albatross as having the greatest wing span.