Which of these is a drake?

[BantammChick]

Hi! So I got four ducks from cackle hatchery in May, and I ordered 3 females and one male, and now I'm not sure which one is the drake! Here are some pictures of them, any help appreciated! If I need to I can try to get some better pictures

 

[fatty and friends]

the one with the black tail feathers

 

[BantammChick]

the one with the black tail feathers

omg I hadn't noticed that! ty!