Explanation:

- Option 1: Vidarbha

- Correct Answer: Vidarbha won the Ranji Trophy for the 2018-19 season. This was their second consecutive title, having also won the previous season (2017-18). The final was held in February 2019, where Vidarbha defeated Saurashtra to claim the championship.

- Option 2: Kerala

- Kerala has been a promising team in recent Ranji Trophy seasons but has not won the title. They reached the semi-finals in 2018-19 but were eliminated by Vidarbha.

- Option 3: Saurashtra

- Saurashtra reached the final of the 2018-19 Ranji Trophy but were the runners-up, losing to Vidarbha in the final match.

- Option 4: Karnataka

- Karnataka is historically a strong team in Indian domestic cricket, with multiple Ranji titles. However, they did not win the 2018-19 season.

Correct Answer: Option 1: Vidarbha