The lion capital pillar is located at:

Correct option is A

The correct answer is option (a):  Sarnath
Explanation:
The Lion Capital of Ashoka is a sculpture that originally adorned the top of the Ashoka Pillar at Sarnath, Uttar Pradesh.
It was erected by Emperor Ashoka around 250 BCE to commemorate the site where the Buddha gave his first sermon after attaining enlightenment (known as the Dharmachakra Pravartan).
Significance:
The Lion Capital is now the National Emblem of India and is found on Indian currency and official documents.
It symbolizes power, courage, confidence, and pride.
Features of the Lion Capital:
The pillar is made of polished sandstone.
The capital has four Asiatic lions standing back to back, representing power and vigilance.
Below the lions is a circular abacus featuring:
Four animals (elephant, horse, bull, and lion) representing the four cardinal directions.
The Dharmachakra (Wheel of Dharma), symbolizing the spread of Buddha's teachings.
 

Other options:

• Barabar Hills: Located in Bihar, known for the oldest surviving rock-cut caves built during Ashoka's reign.
• Dhauli: Located in Odisha, known for Ashoka’s inscriptions and the Shanti Stupa.
  
• Nagarjuna Hills: Also in Bihar, significant for its association with Buddhist and Jain monastic traditions.