Step 1: Understanding the question.
The question asks about the state with the lowest population density in India. Arunachal Pradesh, due to its hilly terrain and less developed infrastructure, has the lowest population density among Indian states.
Step 2: Analyzing the options.
(A) अरुणाचल प्रदेश: Correct — Arunachal Pradesh has the lowest population density in India.
(B) असम: Assam has a higher population density compared to Arunachal Pradesh.
(C) मिजोरम: Mizoram has a low population density, but not the lowest.
(D) सिक्किम: Sikkim also has a relatively low population density, but it is higher than Arunachal Pradesh.
Step 3: Conclusion.
The correct answer is (A) अरुणाचल प्रदेश, as it has the lowest population density in India.