The correct answer is: c) Northeastern monsoons.
The Northeastern monsoons are the dominant wind system in the Indian subcontinent during the summer months. They blow from the Bay of Bengal towards the Indian mainland, bringing with them heavy rainfall. The Eastern Himalayas act as a barrier to these winds, reducing their impact on Arunachal Pradesh.
The Thar Desert winds are dry, hot winds that blow from the Thar Desert in northwestern India towards the Indian subcontinent. They are most common during the summer months. The Western disturbances are cold, dry winds that blow from the Mediterranean Sea towards the Indian subcontinent. They are most common during the winter months. The Southern peninsular winds are warm, moist winds that blow from the Indian Ocean towards the Indian subcontinent. They are most common during the summer months.
The Eastern Himalayas are a mountain range that runs along the eastern border of India. They are the highest mountain range in the world outside of Asia. The Eastern Himalayas act as a barrier to the Northeastern monsoons, reducing their impact on Arunachal Pradesh. This is because the mountains force the winds to rise, which cools and condenses the air, causing the rain to fall on the windward side of the mountains. The leeward side of the mountains, which includes Arunachal Pradesh, is much drier.