Correct Option
The correct option is (a).
Explanation
The Ganga river system is the most significant drainage system in India, originating in the Central Himalayas and traversing the northern plains before draining into the Bay of Bengal. Its course is defined by specific confluence points and transitions from mountainous terrain to alluvial plains.
Statement-wise Analysis
- Statement 1 is Correct: The primary headwater of the Ganga is known as the Bhagirathi. It rises from the Gangotri Glacier near Gaumukh (3,900 m) in the Uttarkashi district of Uttarakhand. At Devprayag, the Bhagirathi meets the Alaknanda; hereafter, the river is known as the Ganga.
- Statement 2 is Incorrect: The Ganga emerges from the mountains onto the plains at Haridwar. Varanasi is located further downstream in the middle Ganga plain of Uttar Pradesh, long after the river has entered the plains.
- Statement 3 is Incorrect: The Yamuna, the westernmost and longest tributary of the Ganga, has its source in the Yamunotri Glacier. It flows parallel to the Ganga for a long distance and joins it at Prayagraj (Allahabad). It is the Son river that joins the Ganga near Patna.
Key Takeaway: The Ganga originates as the Bhagirathi from the Gangotri Glacier, enters the plains at Haridwar, and receives its major right-bank tributary, the Yamuna, at Prayagraj.