The correct answer is (a) sub-humid.
Punjab is a state in northwestern India. It is located in the Indo-Gangetic Plain, which is a sub-humid region. The climate of Punjab is characterized by hot summers and mild winters. The average annual rainfall is about 750 mm.
Rice is a tropical crop that requires a lot of water. It is grown in areas with an average annual rainfall of at least 1,000 mm. The sub-humid climate of Punjab is ideal for growing rice. The state has a well-developed irrigation system that provides the necessary water for rice cultivation.
The other options are incorrect because they are not suitable for growing rice. Semi-arid regions receive less than 500 mm of rainfall per year. Arid regions receive less than 250 mm of rainfall per year. Sub-tropical regions have a hot, humid climate that is not suitable for growing rice.
In conclusion, the sub-humid climate of Punjab is best suited for growing rice. The state has a well-developed irrigation system that provides the necessary water for rice cultivation.