Explanation:

- The IRCTC Buddhist Circuit tour traditionally covers significant Buddhist sites.

- Bodh Gaya: A key destination where Gautama Buddha attained enlightenment.

- Agra: Known primarily for the Taj Mahal, not a typical Buddhist site. It's usually not part of the Buddhist Circuit.

- Sarnath: Near Varanasi, is where Buddha gave his first sermon and is a major Buddhist pilgrimage site.

- Considering these points:

- Option 1 (Only Bodh Gaya): Covers only a Buddhist site.

- Option 2 (Only Bodh Gaya and Agra): Includes Agra, which is not on the Buddhist Circuit.

- Option 3 (Only Bodh Gaya and Sarnath): This combination includes key Buddhist sites.

- Option 4 (Only Agra and Sarnath): Agra is not on the Buddhist Circuit.

- Option 5 (All of the above): Agra is the reason this option is incorrect.

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