Explanation:

- Option 1: Karnataka High Court

- This court was established in 1884. It was originally called the High Court of Mysore.

- Option 2: Calcutta High Court

- This is indeed the oldest High Court. Established in 1862, right after the Indian High Courts Act was legislated.

- It served as a model for other high courts established in India.

- Option 3: Allahabad High Court

- This high court was started in 1866, a few years after the Calcutta High Court.

- Option 4: Delhi High Court

- This court was established much later in 1966.