How did Caravaggio sign the painting ? Why do you think he signed it that way ?

'The Beheading of Saint John the Baptist'

The oil depicts the execution of John the Baptist and is the only work that Caravaggio ever signed.

Explanation:

It is the only work by Caravaggio to bear the artist's signature, which he placed in red blood spilling from the Baptist's cut throat. There is considerable empty space in the image, but because the canvas is quite large the figures are approximately life-sized.

prosumerism is the correct answer.