Question I've ever seen, I've seen ever, I ever saw, etc...

[hirashin]

Hello again, native English speakers,
Which sentence can be used? And which is common?

(a) This is the biggest dog I've ever seen.
(b) This is the biggest dog I've seen ever.
(c) This is the biggest dog I ever have seen.
(d) This is the biggest dog I ever saw.
(e) This is the biggest dog I saw ever.

 

[Michael2]

The only one that I would ever naturally say would be (a)

 

[Lothor]

You might hear (d) sometimes, but I'd teach (a) as correct.

 

[hirashin]

Thanks for the help, Michael2, Lothor, and mdchachi.