Using non-contrasting characters occurring in pair: Incorrect. Keys use contrasting characters, not non-contrasting, in a pair called a couplet.

Generally analytical in nature: Correct. Taxonomic keys are analytical because they involve evaluating specific traits to identify organisms.

Involved in acceptance of two options from a couplet: Incorrect. A couplet involves accepting one statement and rejecting the other.

Same for the different taxonomic levels: Incorrect. Separate, distinct keys are required for different taxonomic categories (family, genus, species).

(E) Using couplets and leads: Correct. A couplet is the pair of contrasting characters, and each statement within it is a lead.Therefore, the correct statements are and (E).

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