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 discussed this concept extensively in his famous Preface to Lyrical Ballads (1800), which served as a manifesto for the Romantic movement in English literature. In this work, Wordsworth explored the relationship between the language of prose and metrical composition (poetry). He argued against the traditional, ornate "poetic diction" of the 18th century, asserting that the language of poetry should closely resemble the real language of men in a state of vivid sensation. His discussions on whether there is, can be, or ought to be a difference between the language of prose and metrical composition laid the foundation for modern poetic theory and sparked major debates on literary style among his contemporaries.