(A) do not represent a new attempt to replace fossil fuels; it
This choice is incorrect because it uses "do not represent" instead of the correct verb form "are not" to match the plural subject "Plant oils."
(B) are not a new attempt to replace fossil fuels; the same one
this choice is incorrect because it introduces the phrase "the same one," which is not necessary and does not logically fit with the context of the sentence.
(C) represent not a new attempt to replace fossil fuels, but one that
this choice incorrectly places "not" after "represent" and adds unnecessary complexity to the sentence.
(D) are not a new attempt to replace fossil fuels, but one that
It correctly uses the verb "are" to agree with the plural subject "Plant oils." Additionally, it introduces the contrast with "but one that," which maintains clarity and logical coherence in the sentence.
Correct choice(E) are not new as an attempt to replace fossil fuels; it
it uses "are not new as an attempt" which is awkward and less clear than the more concise construction in option (D).