The correct answer is: a) High altitude.
Kerala is a state in India that is known for its high altitude. This high altitude is ideal for the cultivation of cash crops like cardamom and coffee. Cardamom and coffee are both plants that require a lot of sunlight and a cool climate. The high altitude in Kerala provides these conditions, which is why these crops are grown so well in the state.
The other options are not as important for the cultivation of cardamom and coffee. Rich soil is important for the growth of many plants, but it is not as important for these two crops. Abundant sunshine is important for both cardamom and coffee, but the high altitude in Kerala provides enough sunlight for these crops to grow well. Well-developed infrastructure is important for the transportation of goods and services, but it is not as important for the cultivation of cardamom and coffee.
In conclusion, the high altitude in Kerala is the most important factor that benefits the cultivation of cash crops like cardamom and coffee.