Which of the following is the flightless bird?

Which of the following is the flightless bird?

A. Pavo cristatus
B. kakapo
C. Passer
D. None of these

The kakapo, also called owl parrot, is a species of large, flightless, nocturnal, ground-dwelling parrot of the super-family Strigopoidea, endemic to New Zealand. It has finely blotched yellow-green plumage, a distinct facial disc, a large grey beak, short legs, large feet, and relatively short wings and tail.
Some other flightless birds you might  know are. Emu, dodo, emperor penguin,  little penguin & common ostrich.