This: a demonstrative pronoun which refers to the very sentence in which it occurs.

the text: "the" is a definite article. If it were omitted, it would subtly change the meaning: without the article, "text" would refer to a piece of text which had not been mentioned or intimated beforehand. With the article, "the text" refers to some text that is somehow known to or perhaps expected by the reader.

which: object of preposition "on."

on: correct, formal English tries to avoid ending sentences with prepositions.