Your first instinct might be to avoid (A), both because the sentence is usually wrong as written, and because (A) is the longest choice. Before committing, however, look closer at all of the choices.

The first underlined word is not always the same. The difference between "strikingly" and "striking" is important. As written, the sentence refers to the Ode as a work that is early and strikingly original; as changed in the last two choices, it refers to the Ode as an original work that is early and striking. "Strikingly original" makes more sense; eliminate (D) and (E).

Choice (B) changes "establishes" to "established." While the Ode was clearly written in the past, be careful when discussing works of art. You may use past tense, for instance when discussing the historical context (e.g. "The Ode on Indolence was written in the 19th century"), but when discussing the work itself, present tense is correct. This eliminates (B). It knocks out (C) as well, in which "establishes" is left intact, but "develops" is changed to "developed." Choice (A) is correct.