Intensive subsistence farming is widely practiced in densely populated areas, particularly in countries like India and China.
Statement I: Correct. Due to high population pressure, land holdings are very small.
Statement II: Correct. Limited use of machinery and more reliance on manual labour is a key characteristic.
Statement III: Incorrect. It is not largely practised in Central Asia, but rather in South and Southeast Asia.
Statement IV: Correct. The yield per unit area is high, but due to heavy dependence on manual labour, the productivity per labour is low.
So, the correct answer is (A): I, II and IV are correct.