This has been a subject of much debate, but which band or performer would we say invented the subgenre known as heavy metal?

The style of music was more or less developed as a product of the electric blues scene in Britain in the late 60's, and it took bands such as Black Sabbath to make it louder and darker. But it was not in complete agreement that the band "invented" heavy metal. They knew the music was heavy, but in a recent interview, Rob Halford of Judas Priest says that HIS band was the first band to be officially metal. What are your thoughts?

I picked all of em :)

I thought today of changing the final selection to "other". It has been noted that Alice Cooper was a person in the development of heavy metal, among others.

I think all of them including Black Sabbath