The correct answer is: A) Coastal plains.
The coastal plains of Karnataka are a major agricultural region in the state. The region is characterized by its fertile soil, warm climate, and abundant rainfall. These conditions are ideal for the cultivation of a wide variety of horticultural crops, including fruits, vegetables, and flowers.
The Western Ghats are a mountain range that runs along the western coast of India. The region is characterized by its cooler climate and higher rainfall than the coastal plains. These conditions are ideal for the cultivation of crops such as coffee, tea, and spices.
The southern dry zone is a region of Karnataka that is characterized by its hot, dry climate. The region is not well-suited for the cultivation of most horticultural crops. However, some crops, such as sugarcane and cotton, can be grown in the region with irrigation.
The northern transitional zone is a region of Karnataka that is located between the coastal plains and the Western Ghats. The region is characterized by its moderate climate and rainfall. This region is well-suited for the cultivation of a wide variety of horticultural crops.
In conclusion, the coastal plains of Karnataka are the most suitable agro-climatic zone for the cultivation of a wide variety of horticultural crops. The region is characterized by its fertile soil, warm climate, and abundant rainfall. These conditions are ideal for the cultivation of a wide variety of crops, including fruits, vegetables, and flowers.