Who said, “there is, there can be and there ought to be the difference between the language of prose and metrical composition”?

The correct option is William Wordsworth.

William Wordsworth expressed this view in his famous Preface to Lyrical Ballads (originally published in 1800). In this seminal work of romantic literary theory, Wordsworth argued against the artificiality of 18th-century "poetic diction." He famously asserted that there is no essential difference between the language of prose and that of metrical composition, believing that poetry should be written in the "language really used by men."

Let us look at the reasoning behind this quote:
Wordsworth wrote: “...it may be safely affirmed, that there neither is, nor can be, any essential difference between the language of prose and metrical composition.”
He believed both prose and poetry share the same medium (words) and serve the same purpose of expressing human emotions, thoughts, and truths. Thus, the correct option representing this perspective is William Wordsworth.