Leave me alone

[Beatrice]

Test No. incompl/inter-23 "Leave me alone", question 9

Alan: If that's how you feel, I'll leave you ..........

(a) lonely
(b) lonesome
(c) alone
(d) apart

Test No. incompl/inter-23 "Leave me alone", answer 9

Alan: If that's how you feel, I'll leave you alone.

Correct answer: (c) alone

Your answer was: incorrect
Alan: If that's how you feel, I'll leave you lonely.
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Can you explain it to me? Why is my initial answer wrong?

[Torsten]

If you leave somebody alone you leave them in peace and don't bother them and that's exactly what is meant in this sentence.

TOEIC listening, photographs: A girl lying on the floor