The correct answer is D.

Explanation: The sentence "Effiong can't kill a snake, ____________ ?" is a negative statement, and it requires a positive question tag for balance. In English, when a statement is negative, the question tag is positive. The subject "Effiong" is female (as indicated by the pronoun "she"), and the correct positive form of "can't" is "can".

- D. can she is the correct positive tag that matches the negative statement.

Other options:
- A. can't she is incorrect because it repeats the negative form.
- B. could she is incorrect because it changes the tense.
- C. isn't it is incorrect because "it" does not match the subject "Effiong."

Thus, the correct sentence is: "Effiong can't kill a snake, can she?"