Step 1: Understanding the question.
The question asks about India's annual population growth rate. Based on the most recent census and demographic data, India's population growth rate stands at approximately 2.6%.
Step 2: Analyzing the options.
(A) 3%: While this is an estimate often used in the past, the current growth rate is closer to 2.6%.
(B) 4%: A growth rate of 4% is too high based on the most recent data.
(C) 2.6%: Correct — The annual growth rate of India's population is currently about 2.6%.
(D) 1.64%: This is a lower estimate, which was more relevant in previous decades.
Step 3: Conclusion.
The correct answer is (C) 2.6%, as it is the most recent annual population growth rate in India.